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RedHat 9 (Linux i386) - man page for csh (redhat section 1)

TCSH(1) 			     General Commands Manual				  TCSH(1)

       tcsh - C shell with file name completion and command line editing

       tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg ...]
       tcsh -l

       tcsh  is  an  enhanced  but  completely	compatible  version of the Berkeley UNIX C shell,
       csh(1).	It is a command language interpreter usable both as an	interactive  login  shell
       and a shell script command processor.  It includes a command-line editor (see The command-
       line editor), programmable word completion (see Completion and listing), spelling  correc-
       tion  (see  Spelling correction), a history mechanism (see History substitution), job con-
       trol (see Jobs) and a C-like syntax.  The NEW FEATURES section  describes  major  enhance-
       ments  of  tcsh	over  csh(1).  Throughout this manual, features of tcsh not found in most
       csh(1) implementations (specifically, the 4.4BSD csh) are labeled with `(+)', and features
       which are present in csh(1) but not usually documented are labeled with `(u)'.

   Argument list processing
       If  the first argument (argument 0) to the shell is `-' then it is a login shell.  A login
       shell can be also specified by invoking the shell with the -l flag as the only argument.

       The rest of the flag arguments are interpreted as follows:

       -b  Forces a ``break'' from option processing, causing any further shell arguments  to  be
	   treated  as	non-option arguments.  The remaining arguments will not be interpreted as
	   shell options.  This may be used to pass options to a shell script  without	confusion
	   or  possible  subterfuge.   The  shell  will not run a set-user ID script without this

       -c  Commands are read from the following argument (which must be present, and  must  be	a
	   single  argument),  stored  in the command shell variable for reference, and executed.
	   Any remaining arguments are placed in the argv shell variable.

       -d  The shell loads the directory stack from ~/.cshdirs as  described  under  Startup  and
	   shutdown, whether or not it is a login shell. (+)

	   Sets the environment variable name to value. (Domain/OS only) (+)

       -e  The shell exits if any invoked command terminates abnormally or yields a non-zero exit

       -f  The shell ignores ~/.tcshrc, and thus starts faster.

       -F  The shell uses fork(2) instead of vfork(2) to spawn processes. (Convex/OS only) (+)

       -i  The shell is interactive and prompts for its top-level input, even if  it  appears  to
	   not	be  a  terminal.   Shells are interactive without this option if their inputs and
	   outputs are terminals.

       -l  The shell is a login shell.	Applicable only if -l is the only flag specified.

       -m  The shell loads ~/.tcshrc even if it does not belong to  the  effective  user.   Newer
	   versions of su(1) can pass -m to the shell. (+)

       -n  The	shell  parses  commands  but does not execute them.  This aids in debugging shell

       -q  The shell accepts SIGQUIT (see Signal handling) and behaves when it is  used  under	a
	   debugger.  Job control is disabled. (u)

       -s  Command input is taken from the standard input.

       -t  The	shell reads and executes a single line of input.  A `\' may be used to escape the
	   newline at the end of this line and continue onto another line.

       -v  Sets the verbose shell variable, so that command input is echoed after history substi-

       -x  Sets  the  echo  shell variable, so that commands are echoed immediately before execu-

       -V  Sets the verbose shell variable even before executing ~/.tcshrc.

       -X  Is to -x as -V is to -v.

       After processing of flag arguments, if arguments remain but none of the -c, -i, -s, or  -t
       options	were  given,  the  first  argument is taken as the name of a file of commands, or
       ``script'', to be executed.  The shell opens this file and saves  its  name  for  possible
       resubstitution by `$0'.	Because many systems use either the standard version 6 or version
       7 shells whose shell scripts are not compatible with this shell, the  shell  uses  such	a
       `standard'  shell  to execute a script whose first character is not a `#', i.e., that does
       not start with a comment.

       Remaining arguments are placed in the argv shell variable.

   Startup and shutdown
       A login shell begins by executing  commands  from  the  system  files  /etc/csh.cshrc  and
       /etc/csh.login.	 It then executes commands from files in the user's home directory: first
       ~/.tcshrc (+) or, if ~/.tcshrc is not found, ~/.cshrc, then ~/.history (or  the	value  of
       the  histfile  shell variable), then ~/.login, and finally ~/.cshdirs (or the value of the
       dirsfile shell variable) (+).  The shell may read /etc/csh.login before instead	of  after
       /etc/csh.cshrc, and ~/.login before instead of after ~/.tcshrc or ~/.cshrc and ~/.history,
       if so compiled; see the version shell variable. (+)

       Non-login shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on startup.

       For examples of startup files, please consult http://tcshrc.sourceforge.net.

       Commands like stty(1) and tset(1), which need be run only once per login,  usually  go  in
       one's  ~/.login	file.	Users  who need to use the same set of files with both csh(1) and
       tcsh can have only a ~/.cshrc which checks for the existence of the  tcsh  shell  variable
       (q.v.)  before  using  tcsh-specific commands, or can have both a ~/.cshrc and a ~/.tcshrc
       which sources  (see  the  builtin  command)  ~/.cshrc.	The  rest  of  this  manual  uses
       `~/.tcshrc' to mean `~/.tcshrc or, if ~/.tcshrc is not found, ~/.cshrc'.

       In the normal case, the shell begins reading commands from the terminal, prompting with `>
       '.  (Processing of arguments and the use of the shell to process files containing  command
       scripts	are described later.)  The shell repeatedly reads a line of command input, breaks
       it into words, places it on the command history list, parses it and executes each  command
       in the line.

       One  can  log  out by typing `^D' on an empty line, `logout' or `login' or via the shell's
       autologout mechanism (see the autologout shell variable).  When a login	shell  terminates
       it sets the logout shell variable to `normal' or `automatic' as appropriate, then executes
       commands from the files /etc/csh.logout and ~/.logout.  The shell may drop DTR  on  logout
       if so compiled; see the version shell variable.

       The  names of the system login and logout files vary from system to system for compatibil-
       ity with different csh(1) variants; see FILES.

       We first describe The command-line editor.  The Completion and listing and  Spelling  cor-
       rection	sections  describe  two sets of functionality that are implemented as editor com-
       mands but which deserve their own treatment.  Finally, Editor commands lists and describes
       the editor commands specific to the shell and their default bindings.

   The command-line editor (+)
       Command-line  input can be edited using key sequences much like those used in GNU Emacs or
       vi(1).  The editor is active only when the edit shell variable is  set,	which  it  is  by
       default	in  interactive shells.  The bindkey builtin can display and change key bindings.
       Emacs-style key bindings are used by default (unless the shell was compiled otherwise; see
       the  version shell variable), but bindkey can change the key bindings to vi-style bindings
       en masse.

       The shell always binds the arrow keys (as defined in the TERMCAP environment variable) to

	   down    down-history
	   up	   up-history
	   left    backward-char
	   right   forward-char

       unless doing so would alter another single-character binding.  One can set the  arrow  key
       escape sequences to the empty string with settc to prevent these bindings.  The ANSI/VT100
       sequences for arrow keys are always bound.

       Other key bindings are, for the most part, what Emacs and vi(1) users would expect and can
       easily  be displayed by bindkey, so there is no need to list them here.	Likewise, bindkey
       can list the editor commands with a short description of each.

       Note that editor commands do not have the same notion of a ``word''  as	does  the  shell.
       The  editor  delimits words with any non-alphanumeric characters not in the shell variable
       wordchars, while the shell recognizes only whitespace and some of the characters with spe-
       cial meanings to it, listed under Lexical structure.

   Completion and listing (+)
       The  shell is often able to complete words when given a unique abbreviation.  Type part of
       a word (for example `ls /usr/lost') and hit the tab key to run  the  complete-word  editor
       command.   The  shell  completes the filename `/usr/lost' to `/usr/lost+found/', replacing
       the incomplete word with the complete word in the input buffer.	(Note the  terminal  `/';
       completion  adds a `/' to the end of completed directories and a space to the end of other
       completed words, to speed typing and provide a visual indicator of successful  completion.
       The addsuffix shell variable can be unset to prevent this.)  If no match is found (perhaps
       `/usr/lost+found' doesn't exist), the terminal bell rings.  If the word	is  already  com-
       plete (perhaps there is a `/usr/lost' on your system, or perhaps you were thinking too far
       ahead and typed the whole thing) a `/' or space is added to the end if  it  isn't  already

       Completion works anywhere in the line, not at just the end; completed text pushes the rest
       of the line to the right.  Completion in the middle of a word often  results  in  leftover
       characters to the right of the cursor that need to be deleted.

       Commands  and  variables  can  be  completed  in  much  the same way.  For example, typing
       `em[tab]' would complete `em' to `emacs' if emacs were the only	command  on  your  system
       beginning with `em'.  Completion can find a command in any directory in path or if given a
       full pathname.  Typing `echo $ar[tab]' would complete `$ar' to `$argv' if no  other  vari-
       able began with `ar'.

       The  shell  parses  the	input  buffer  to determine whether the word you want to complete
       should be completed as a filename, command or variable.	The first word in the buffer  and
       the  first  word  following `;', `|', `|&', `&&' or `||' is considered to be a command.	A
       word beginning with `$' is considered to be a variable.	Anything else is a filename.   An
       empty line is `completed' as a filename.

       You  can  list  the  possible  completions of a word at any time by typing `^D' to run the
       delete-char-or-list-or-eof editor command.  The shell lists the possible completions using
       the ls-F builtin (q.v.)	and reprints the prompt and unfinished command line, for example:

	   > ls /usr/l[^D]
	   lbin/       lib/	   local/      lost+found/
	   > ls /usr/l

       If  the	autolist  shell  variable  is set, the shell lists the remaining choices (if any)
       whenever completion fails:

	   > set autolist
	   > nm /usr/lib/libt[tab]
	   libtermcap.a@ libtermlib.a@
	   > nm /usr/lib/libterm

       If autolist is set to `ambiguous', choices are listed only when completion fails and  adds
       no new characters to the word being completed.

       A  filename  to	be  completed can contain variables, your own or others' home directories
       abbreviated with `~' (see Filename substitution) and directory stack  entries  abbreviated
       with `=' (see Directory stack substitution).  For example,

	   > ls ~k[^D]
	   kahn    kas	   kellogg
	   > ls ~ke[tab]
	   > ls ~kellogg/


	   > set local = /usr/local
	   > ls $lo[tab]
	   > ls $local/[^D]
	   bin/ etc/ lib/ man/ src/
	   > ls $local/

       Note  that variables can also be expanded explicitly with the expand-variables editor com-

       delete-char-or-list-or-eof lists at only the end of the line; in the middle of a  line  it
       deletes	the  character	under  the  cursor  and  on  an empty line it logs one out or, if
       ignoreeof is set, does nothing.	`M-^D', bound to the editor command  list-choices,  lists
       completion  possibilities  anywhere on a line, and list-choices (or any one of the related
       editor commands that do or don't delete, list and/or log out, listed under delete-char-or-
       list-or-eof) can be bound to `^D' with the bindkey builtin command if so desired.

       The  complete-word-fwd  and  complete-word-back	editor commands (not bound to any keys by
       default) can be used to cycle up and  down  through  the  list  of  possible  completions,
       replacing the current word with the next or previous word in the list.

       The  shell  variable fignore can be set to a list of suffixes to be ignored by completion.
       Consider the following:

	   > ls
	   Makefile	   condiments.h~   main.o	   side.c
	   README	   main.c	   meal 	   side.o
	   condiments.h    main.c~
	   > set fignore = (.o \~)
	   > emacs ma[^D]
	   main.c   main.c~  main.o
	   > emacs ma[tab]
	   > emacs main.c

       `main.c~' and `main.o' are ignored by completion (but not listing), because  they  end  in
       suffixes  in fignore.  Note that a `\' was needed in front of `~' to prevent it from being
       expanded to home as described under Filename substitution.  fignore is ignored if only one
       completion is possible.

       If the complete shell variable is set to `enhance', completion 1) ignores case and 2) con-
       siders periods, hyphens and underscores (`.', `-' and  `_')  to	be  word  separators  and
       hyphens and underscores to be equivalent.  If you had the following files

	   comp.lang.c	    comp.lang.perl   comp.std.c++
	   comp.lang.c++    comp.std.c

       and  typed  `mail  -f  c.l.c[tab]', it would be completed to `mail -f comp.lang.c', and ^D
       would  list  `comp.lang.c'  and	`comp.lang.c++'.   `mail  -f   c..c++[^D]'   would   list
       `comp.lang.c++' and `comp.std.c++'.  Typing `rm a--file[^D]' in the following directory

	   A_silly_file    a-hyphenated-file	another_silly_file

       would list all three files, because case is ignored and hyphens and underscores are equiv-
       alent.  Periods, however, are not equivalent to hyphens or underscores.

       Completion and listing are affected by several other shell variables: recexact can be  set
       to  complete  on the shortest possible unique match, even if more typing might result in a
       longer match:

	   > ls
	   fodder   foo      food     foonly
	   > set recexact
	   > rm fo[tab]

       just beeps, because `fo' could expand to `fod' or `foo', but if we type another `o',

	   > rm foo[tab]
	   > rm foo

       the completion completes on `foo', even though `food' and `foonly' also match.  autoexpand
       can  be set to run the expand-history editor command before each completion attempt, auto-
       correct can be set to spelling-correct the word to be completed (see Spelling  correction)
       before  each  completion attempt and correct can be set to complete commands automatically
       after one hits `return'.  matchbeep can be set to make completion beep or not  beep  in	a
       variety of situations, and nobeep can be set to never beep at all.  nostat can be set to a
       list of directories and/or patterns that match directories to prevent the completion mech-
       anism  from stat(2)ing those directories.  listmax and listmaxrows can be set to limit the
       number of items and rows (respectively) that are  listed  without  asking  first.   recog-
       nize_only_executables can be set to make the shell list only executables when listing com-
       mands, but it is quite slow.

       Finally, the complete builtin command can be used to tell the shell how to complete  words
       other than filenames, commands and variables.  Completion and listing do not work on glob-
       patterns (see Filename substitution), but the list-glob and  expand-glob  editor  commands
       perform equivalent functions for glob-patterns.

   Spelling correction (+)
       The  shell can sometimes correct the spelling of filenames, commands and variable names as
       well as completing and listing them.

       Individual words can be spelling-corrected with the  spell-word	editor	command  (usually
       bound  to M-s and M-S) and the entire input buffer with spell-line (usually bound to M-$).
       The correct shell variable can be set to `cmd' to correct the command  name  or	`all'  to
       correct	the  entire line each time return is typed, and autocorrect can be set to correct
       the word to be completed before each completion attempt.

       When spelling correction is invoked in any of these ways and the  shell	thinks	that  any
       part of the command line is misspelled, it prompts with the corrected line:

	   > set correct = cmd
	   > lz /usr/bin
	   CORRECT>ls /usr/bin (y|n|e|a)?

       One  can  answer  `y' or space to execute the corrected line, `e' to leave the uncorrected
       command in the input buffer, `a' to abort the command as if `^C' had been  hit,	and  any-
       thing else to execute the original line unchanged.

       Spelling  correction  recognizes  user-defined  completions (see the complete builtin com-
       mand).  If an input word in a position for which a completion is defined resembles a  word
       in  the completion list, spelling correction registers a misspelling and suggests the lat-
       ter word as a correction.  However, if the input word does not match any of  the  possible
       completions for that position, spelling correction does not register a misspelling.

       Like  completion,  spelling correction works anywhere in the line, pushing the rest of the
       line to the right and possibly leaving extra characters to the right of the cursor.

       Beware: spelling correction is not guaranteed to work the way one intends, and is provided
       mostly as an experimental feature.  Suggestions and improvements are welcome.

   Editor commands (+)
       `bindkey' lists key bindings and `bindkey -l' lists and briefly describes editor commands.
       Only new or especially interesting editor commands are described here.  See  emacs(1)  and
       vi(1) for descriptions of each editor's key bindings.

       The  character  or characters to which each command is bound by default is given in paren-
       theses.	`^character' means a control character and `M-character' a meta character,  typed
       as  escape-character  on terminals without a meta key.  Case counts, but commands that are
       bound to letters by default are bound to both lower-  and  uppercase  letters  for  conve-

       complete-word (tab)
	       Completes a word as described under Completion and listing.

       complete-word-back (not bound)
	       Like complete-word-fwd, but steps up from the end of the list.

       complete-word-fwd (not bound)
	       Replaces the current word with the first word in the list of possible completions.
	       May be repeated to step down through the list.  At the end of the list, beeps  and
	       reverts to the incomplete word.

       complete-word-raw (^X-tab)
	       Like complete-word, but ignores user-defined completions.

       copy-prev-word (M-^_)
	       Copies  the  previous  word  in	the current line into the input buffer.  See also

       dabbrev-expand (M-/)
	       Expands the current word to the most recent preceding one for which the current is
	       a  leading  substring,  wrapping  around  the  history  list  (once) if necessary.
	       Repeating dabbrev-expand without any intervening typing changes to the next previ-
	       ous word etc., skipping identical matches much like history-search-backward does.

       delete-char (not bound)
	       Deletes the character under the cursor.	See also delete-char-or-list-or-eof.

       delete-char-or-eof (not bound)
	       Does  delete-char  if  there  is a character under the cursor or end-of-file on an
	       empty line.  See also delete-char-or-list-or-eof.

       delete-char-or-list (not bound)
	       Does delete-char if there is a character under the cursor or list-choices  at  the
	       end of the line.  See also delete-char-or-list-or-eof.

       delete-char-or-list-or-eof (^D)
	       Does delete-char if there is a character under the cursor, list-choices at the end
	       of the line or end-of-file on an empty line.  See also those three commands,  each
	       of  which  does	only a single action, and delete-char-or-eof, delete-char-or-list
	       and list-or-eof, each of which does a different two out of the three.

       down-history (down-arrow, ^N)
	       Like up-history, but steps down, stopping at the original input line.

       end-of-file (not bound)
	       Signals an end of file, causing the shell to exit unless the ignoreeof shell vari-
	       able (q.v.) is set to prevent this.  See also delete-char-or-list-or-eof.

       expand-history (M-space)
	       Expands history substitutions in the current word.  See History substitution.  See
	       also magic-space, toggle-literal-history and the autoexpand shell variable.

       expand-glob (^X-*)
	       Expands the glob-pattern to the left of the cursor.  See Filename substitution.

       expand-line (not bound)
	       Like expand-history, but expands history substitutions in each word in  the  input

       expand-variables (^X-$)
	       Expands the variable to the left of the cursor.	See Variable substitution.

       history-search-backward (M-p, M-P)
	       Searches  backwards through the history list for a command beginning with the cur-
	       rent contents of the input buffer up to the cursor and copies it  into  the  input
	       buffer.	 The search string may be a glob-pattern (see Filename substitution) con-
	       taining `*', `?', `[]' or `{}'.	up-history and down-history will proceed from the
	       appropriate point in the history list.  Emacs mode only.  See also history-search-
	       forward and i-search-back.

       history-search-forward (M-n, M-N)
	       Like history-search-backward, but searches forward.

       i-search-back (not bound)
	       Searches backward like history-search-backward, copies the first  match	into  the
	       input  buffer  with  the  cursor positioned at the end of the pattern, and prompts
	       with `bck: ' and the first match.  Additional characters may be	typed  to  extend
	       the  search,  i-search-back  may be typed to continue searching with the same pat-
	       tern, wrapping around the history list if necessary, (i-search-back must be  bound
	       to a single character for this to work) or one of the following special characters
	       may be typed:

		   ^W	   Appends the rest of the word under the cursor to the search pattern.
		   delete (or any character bound to backward-delete-char)
			   Undoes the effect of the last character typed and deletes a	character
			   from the search pattern if appropriate.
		   ^G	   If  the  previous search was successful, aborts the entire search.  If
			   not, goes back to the last successful search.
		   escape  Ends the search, leaving the current line in the input buffer.

	       Any other character not bound to self-insert-command terminates the search,  leav-
	       ing the current line in the input buffer, and is then interpreted as normal input.
	       In particular, a carriage return causes the current line to  be	executed.   Emacs
	       mode only.  See also i-search-fwd and history-search-backward.

       i-search-fwd (not bound)
	       Like i-search-back, but searches forward.

       insert-last-word (M-_)
	       Inserts	the  last  word  of the previous input line (`!$') into the input buffer.
	       See also copy-prev-word.

       list-choices (M-^D)
	       Lists completion possibilities as described under  Completion  and  listing.   See
	       also delete-char-or-list-or-eof and list-choices-raw.

       list-choices-raw (^X-^D)
	       Like list-choices, but ignores user-defined completions.

       list-glob (^X-g, ^X-G)
	       Lists  (via  the ls-F builtin) matches to the glob-pattern (see Filename substitu-
	       tion) to the left of the cursor.

       list-or-eof (not bound)
	       Does list-choices or end-of-file on an empty line.  See also  delete-char-or-list-

       magic-space (not bound)
	       Expands	history  substitutions	in  the  current  line,  like expand-history, and
	       appends a space.  magic-space is designed to be bound to the space bar, but is not
	       bound by default.

       normalize-command (^X-?)
	       Searches  for  the  current word in PATH and, if it is found, replaces it with the
	       full path to the executable.  Special characters are quoted.  Aliases are expanded
	       and  quoted but commands within aliases are not.  This command is useful with com-
	       mands that take commands as arguments, e.g., `dbx' and `sh -x'.

       normalize-path (^X-n, ^X-N)
	       Expands the current word as described under the `expand' setting of  the  symlinks
	       shell variable.

       overwrite-mode (unbound)
	       Toggles between input and overwrite modes.

       run-fg-editor (M-^Z)
	       Saves  the current input line and looks for a stopped job with a name equal to the
	       last component of the file name part of the EDITOR  or  VISUAL  environment  vari-
	       ables,  or,  if	neither  is  set,  `ed'  or  `vi'.  If such a job is found, it is
	       restarted as if `fg %job' had been typed.  This is used to toggle back  and  forth
	       between	an editor and the shell easily.  Some people bind this command to `^Z' so
	       they can do this even more easily.

       run-help (M-h, M-H)
	       Searches for documentation on the current command, using the same notion of  `cur-
	       rent command' as the completion routines, and prints it.  There is no way to use a
	       pager; run-help is designed for short help files.  If the special  alias  helpcom-
	       mand  is defined, it is run with the command name as a sole argument.  Else, docu-
	       mentation should be in a file named command.help, command.1, command.6,	command.8
	       or command, which should be in one of the directories listed in the HPATH environ-
	       ment variable.  If there is more than one help file only the first is printed.

       self-insert-command (text characters)
	       In insert mode (the default), inserts the typed	character  into  the  input  line
	       after  the  character under the cursor.	In overwrite mode, replaces the character
	       under the cursor with the typed character.  The input mode is  normally	preserved
	       between	lines,	but the inputmode shell variable can be set to `insert' or `over-
	       write' to put the editor in that mode at the beginning of  each	line.	See  also

       sequence-lead-in (arrow prefix, meta prefix, ^X)
	       Indicates that the following characters are part of a multi-key sequence.  Binding
	       a command to a multi-key sequence really creates two bindings: the first character
	       to  sequence-lead-in  and the whole sequence to the command.  All sequences begin-
	       ning with a character bound to sequence-lead-in are  effectively  bound	to  unde-
	       fined-key unless bound to another command.

       spell-line (M-$)
	       Attempts  to  correct  the  spelling of each word in the input buffer, like spell-
	       word, but ignores words whose first character is one of `-', `!', `^' or  `%',  or
	       which  contain `\', `*' or `?', to avoid problems with switches, substitutions and
	       the like.  See Spelling correction.

       spell-word (M-s, M-S)
	       Attempts to correct the spelling of the current word as described  under  Spelling
	       correction.  Checks each component of a word which appears to be a pathname.

       toggle-literal-history (M-r, M-R)
	       Expands	or  `unexpands'  history  substitutions  in  the  input buffer.  See also
	       expand-history and the autoexpand shell variable.

       undefined-key (any unbound key)

       up-history (up-arrow, ^P)
	       Copies the previous entry in the history list into the input buffer.   If  histlit
	       is  set,  uses  the literal form of the entry.  May be repeated to step up through
	       the history list, stopping at the top.

       vi-search-back (?)
	       Prompts with `?' for a search string (which may be a glob-pattern,  as  with  his-
	       tory-search-backward),  searches  for it and copies it into the input buffer.  The
	       bell rings if no match is found.  Hitting return ends the search  and  leaves  the
	       last  match  in the input buffer.  Hitting escape ends the search and executes the
	       match.  vi mode only.

       vi-search-fwd (/)
	       Like vi-search-back, but searches forward.

       which-command (M-?)
	       Does a which (see the description of the builtin command) on the first word of the
	       input buffer.

   Lexical structure
       The  shell  splits input lines into words at blanks and tabs.  The special characters `&',
       `|', `;', `<', `>', `(', and `)' and the doubled characters `&&', `||', `<<' and `>>'  are
       always separate words, whether or not they are surrounded by whitespace.

       When  the  shell's input is not a terminal, the character `#' is taken to begin a comment.
       Each `#' and the rest of the input line on which it appears is  discarded  before  further

       A  special  character  (including a blank or tab) may be prevented from having its special
       meaning, and possibly made part of another word, by preceding it with a backslash (`\') or
       enclosing  it  in single (`''), double (`"') or backward (``') quotes.  When not otherwise
       quoted a newline preceded by a `\' is equivalent  to  a	blank,	but  inside  quotes  this
       sequence results in a newline.

       Furthermore, all Substitutions (see below) except History substitution can be prevented by
       enclosing the strings (or parts of strings) in which they appear with single quotes or  by
       quoting	the  crucial  character(s) (e.g., `$' or ``' for Variable substitution or Command
       substitution respectively) with `\'.  (Alias substitution is no exception: quoting in  any
       way  any  character of a word for which an alias has been defined prevents substitution of
       the alias.  The usual way of quoting an alias is to precede it with a backslash.)  History
       substitution  is  prevented  by backslashes but not by single quotes.  Strings quoted with
       double or backward quotes undergo Variable  substitution  and  Command  substitution,  but
       other substitutions are prevented.

       Text  inside  single or double quotes becomes a single word (or part of one).  Metacharac-
       ters in these strings, including blanks and tabs, do not form separate words.  Only in one
       special	case  (see  Command substitution below) can a double-quoted string yield parts of
       more than one word; single-quoted strings never do.  Backward  quotes  are  special:  they
       signal Command substitution (q.v.), which may result in more than one word.

       Quoting complex strings, particularly strings which themselves contain quoting characters,
       can be confusing.  Remember that quotes need not be used as they are in human writing!  It
       may be easier to quote not an entire string, but only those parts of the string which need
       quoting, using different types of quoting to do so if appropriate.

       The backslash_quote shell variable (q.v.) can be set to make backslashes always quote `\',
       `'',  and  `"'.	 (+)  This may make complex quoting tasks easier, but it can cause syntax
       errors in csh(1) scripts.

       We now describe the various transformations the shell performs on the input in  the  order
       in which they occur.  We note in passing the data structures involved and the commands and
       variables which affect them.  Remember that substitutions can be prevented by  quoting  as
       described under Lexical structure.

   History substitution
       Each  command,  or  ``event'',  input from the terminal is saved in the history list.  The
       previous command is always saved, and the history shell variable can be set to a number to
       save  that  many  commands.   The  histdup shell variable can be set to not save duplicate
       events or consecutive duplicate events.

       Saved commands are numbered sequentially from 1 and stamped with the time.  It is not usu-
       ally  necessary to use event numbers, but the current event number can be made part of the
       prompt by placing an `!' in the prompt shell variable.

       The shell actually saves history in expanded  and  literal  (unexpanded)  forms.   If  the
       histlit	shell  variable  is  set, commands that display and store history use the literal

       The history builtin command can print, store in a file, restore and clear the history list
       at  any time, and the savehist and histfile shell variables can be can be set to store the
       history list automatically on logout and restore it on login.

       History substitutions introduce words from the history list into the input stream,  making
       it easy to repeat commands, repeat arguments of a previous command in the current command,
       or fix spelling mistakes in the previous command with little typing and a high  degree  of

       History	substitutions begin with the character `!'.  They may begin anywhere in the input
       stream, but they do not nest.  The `!' may be preceded by a `\'	to  prevent  its  special
       meaning;  for  convenience, a `!' is passed unchanged when it is followed by a blank, tab,
       newline, `=' or `('.  History substitutions also occur when an input line begins with `^'.
       This  special abbreviation will be described later.  The characters used to signal history
       substitution (`!' and `^') can be changed by setting the histchars  shell  variable.   Any
       input line which contains a history substitution is printed before it is executed.

       A history substitution may have an ``event specification'', which indicates the event from
       which words are to be taken, a ``word designator'', which selects  particular  words  from
       the chosen event, and/or a ``modifier'', which manipulates the selected words.

       An event specification can be

	   n	   A number, referring to a particular event
	   -n	   An offset, referring to the event n before the current event
	   #	   The current event.  This should be used carefully in csh(1), where there is no
		   check for recursion.  tcsh allows 10 levels of recursion.  (+)
	   !	   The previous event (equivalent to `-1')
	   s	   The most recent event whose first word begins with the string s
	   ?s?	   The most recent event which contains the string s.	The  second  `?'  can  be
		   omitted if it is immediately followed by a newline.

       For example, consider this bit of someone's history list:

	    9  8:30    nroff -man wumpus.man
	   10  8:31    cp wumpus.man wumpus.man.old
	   11  8:36    vi wumpus.man
	   12  8:37    diff wumpus.man.old wumpus.man

       The commands are shown with their event numbers and time stamps.  The current event, which
       we haven't typed in yet, is event 13.  `!11' and `!-2' refer to event 11.  `!!' refers  to
       the  previous  event,  12.   `!!'  can be abbreviated `!' if it is followed by `:' (`:' is
       described below).  `!n' refers to event 9, which begins with `n'.  `!?old?' also refers to
       event  12, which contains `old'.  Without word designators or modifiers history references
       simply expand to the entire event, so we might type `!cp' to  redo  the	copy  command  or
       `!!|more' if the `diff' output scrolled off the top of the screen.

       History	references  may  be insulated from the surrounding text with braces if necessary.
       For example, `!vdoc' would look for a command beginning with `vdoc', and, in this example,
       not  find  one,	but  `!{v}doc' would expand unambiguously to `vi wumpus.mandoc'.  Even in
       braces, history substitutions do not nest.

       (+) While csh(1) expands, for example, `!3d' to event 3 with the letter	`d'  appended  to
       it,  tcsh  expands it to the last event beginning with `3d'; only completely numeric argu-
       ments are treated as event numbers.  This makes it possible  to	recall	events	beginning
       with numbers.  To expand `!3d' as in csh(1) say `!\3d'.

       To  select words from an event we can follow the event specification by a `:' and a desig-
       nator for the desired words.  The words of an input line are numbered from  0,  the  first
       (usually  command) word being 0, the second word (first argument) being 1, etc.	The basic
       word designators are:

	   0	   The first (command) word
	   n	   The nth argument
	   ^	   The first argument, equivalent to `1'
	   $	   The last argument
	   %	   The word matched by an ?s? search
	   x-y	   A range of words
	   -y	   Equivalent to `0-y'
	   *	   Equivalent to `^-$', but returns nothing if the event contains only 1 word
	   x*	   Equivalent to `x-$'
	   x-	   Equivalent to `x*', but omitting the last word (`$')

       Selected words are inserted into the command line separated by single blanks.   For  exam-
       ple,  the  `diff'  command in the previous example might have been typed as `diff !!:1.old
       !!:1' (using `:1' to select the first argument from the previous  event)  or  `diff  !-2:2
       !-2:1'  to  select  and swap the arguments from the `cp' command.  If we didn't care about
       the order of the `diff' we might have said `diff !-2:1-2' or  simply  `diff  !-2:*'.   The
       `cp'  command  might have been written `cp wumpus.man !#:1.old', using `#' to refer to the
       current event.  `!n:- hurkle.man' would reuse the first two words from the `nroff' command
       to say `nroff -man hurkle.man'.

       The  `:' separating the event specification from the word designator can be omitted if the
       argument selector begins with a `^', `$', `*', `%' or `-'.  For example, our  `diff'  com-
       mand might have been `diff !!^.old !!^' or, equivalently, `diff !!$.old !!$'.  However, if
       `!!' is abbreviated `!', an argument selector beginning with `-' will be interpreted as an
       event specification.

       A history reference may have a word designator but no event specification.  It then refer-
       ences the previous command.  Continuing our `diff' example,  we	could  have  said  simply
       `diff !^.old !^' or, to get the arguments in the opposite order, just `diff !*'.

       The  word  or words in a history reference can be edited, or ``modified'', by following it
       with one or more modifiers, each preceded by a `:':

	   h	   Remove a trailing pathname component, leaving the head.
	   t	   Remove all leading pathname components, leaving the tail.
	   r	   Remove a filename extension `.xxx', leaving the root name.
	   e	   Remove all but the extension.
	   u	   Uppercase the first lowercase letter.
	   l	   Lowercase the first uppercase letter.
	   s/l/r/  Substitute l for r.	l is simply a string like r, not a regular expression  as
		   in the eponymous ed(1) command.  Any character may be used as the delimiter in
		   place of `/'; a `\' can be used to quote the delimiter inside l  and  r.   The
		   character  `&'  in the r is replaced by l; `\' also quotes `&'.  If l is empty
		   (``''), the l from a previous substitution or the  s  from  a  previous  `?s?'
		   event  specification  is used.  The trailing delimiter may be omitted if it is
		   immediately followed by a newline.
	   &	   Repeat the previous substitution.
	   g	   Apply the following modifier once to each word.
	   a (+)   Apply the following modifier as many times as possible to a single word.   `a'
		   and	`g'  can  be  used together to apply a modifier globally.  In the current
		   implementation, using the `a' and `s' modifiers together can lead to an  infi-
		   nite  loop.	 For  example,	`:as/f/ff/'  will never terminate.  This behavior
		   might change in the future.
	   p	   Print the new command line but do not execute it.
	   q	   Quote the substituted words, preventing further substitutions.
	   x	   Like q, but break into words at blanks, tabs and newlines.

       Modifiers are applied to only the first modifiable word (unless `g' is used).   It  is  an
       error for no word to be modifiable.

       For  example,  the  `diff' command might have been written as `diff wumpus.man.old !#^:r',
       using `:r' to remove `.old' from the first argument on the same line  (`!#^').	We  could
       say `echo hello out there', then `echo !*:u' to capitalize `hello', `echo !*:au' to say it
       out loud, or `echo !*:agu' to really shout.  We might follow `mail -s "I forgot	my  pass-
       word" rot' with `!:s/rot/root' to correct the spelling of `root' (but see Spelling correc-
       tion for a different approach).

       There is a special abbreviation for substitutions.  `^', when it is the first character on
       an  input  line, is equivalent to `!:s^'.  Thus we might have said `^rot^root' to make the
       spelling correction in the previous example.  This is the only history substitution  which
       does not explicitly begin with `!'.

       (+)  In	csh  as such, only one modifier may be applied to each history or variable expan-
       sion.  In tcsh, more than one may be used, for example

	   % mv wumpus.man /usr/man/man1/wumpus.1
	   % man !$:t:r
	   man wumpus

       In csh, the result would be `wumpus.1:r'.  A substitution followed by a colon may need  to
       be insulated from it with braces:

	   > mv a.out /usr/games/wumpus
	   > setenv PATH !$:h:$PATH
	   Bad ! modifier: $.
	   > setenv PATH !{-2$:h}:$PATH
	   setenv PATH /usr/games:/bin:/usr/bin:.

       The  first  attempt  would  succeed in csh but fails in tcsh, because tcsh expects another
       modifier after the second colon rather than `$'.

       Finally, history can be accessed through the editor as well as through  the  substitutions
       just described.	The up- and down-history, history-search-backward and -forward, i-search-
       back and -fwd, vi-search-back and -fwd, copy-prev-word and  insert-last-word  editor  com-
       mands search for events in the history list and copy them into the input buffer.  The tog-
       gle-literal-history editor command switches between the expanded and literal forms of his-
       tory  lines  in the input buffer.  expand-history and expand-line expand history substitu-
       tions in the current word and in the entire input buffer respectively.

   Alias substitution
       The shell maintains a list of aliases which can be set, unset and printed by the alias and
       unalias	commands.  After a command line is parsed into simple commands (see Commands) the
       first word of each command, left-to-right, is checked to see if it has an alias.   If  so,
       the  first  word  is replaced by the alias.  If the alias contains a history reference, it
       undergoes History substitution (q.v.) as though the original  command  were  the  previous
       input  line.  If the alias does not contain a history reference, the argument list is left

       Thus if the alias for `ls' were `ls -l' the command `ls /usr' would become `ls  -l  /usr',
       the  argument  list  here  being  undisturbed.	If  the  alias for `lookup' were `grep !^
       /etc/passwd' then `lookup bill' would become `grep bill /etc/passwd'.  Aliases can be used
       to  introduce  parser  metasyntax.   For  example,  `alias print 'pr \!* | lpr'' defines a
       ``command'' (`print') which pr(1)s its arguments to the line printer.

       Alias substitution is repeated until the first word of the command has no  alias.   If  an
       alias  substitution  does  not  change  the  first word (as in the previous example) it is
       flagged to prevent a loop.  Other loops are detected and cause an error.

       Some aliases are referred to by the shell; see Special aliases.

   Variable substitution
       The shell maintains a list of variables, each of which has as value a list of zero or more
       words.	The values of shell variables can be displayed and changed with the set and unset
       commands.  The system maintains its own list of ``environment'' variables.  These  can  be
       displayed and changed with printenv, setenv and unsetenv.

       (+)  Variables  may be made read-only with `set -r' (q.v.)  Read-only variables may not be
       modified or unset; attempting to do so will cause an error.  Once made read-only, a  vari-
       able  cannot be made writable, so `set -r' should be used with caution.	Environment vari-
       ables cannot be made read-only.

       Some variables are set by the shell or referred to by it.  For instance, the argv variable
       is  an image of the shell's argument list, and words of this variable's value are referred
       to in special ways.  Some of the variables referred to by the shell are toggles; the shell
       does  not  care	what their value is, only whether they are set or not.	For instance, the
       verbose variable is a toggle which causes command input to be echoed.  The -v command line
       option sets this variable.  Special shell variables lists all variables which are referred
       to by the shell.

       Other operations treat variables numerically.  The `@' command  permits	numeric  calcula-
       tions  to  be  performed and the result assigned to a variable.	Variable values are, how-
       ever, always represented as (zero or more) strings.  For the purposes  of  numeric  opera-
       tions,  the  null  string is considered to be zero, and the second and subsequent words of
       multi-word values are ignored.

       After the input line is aliased and parsed, and before each command is executed,  variable
       substitution  is  performed  keyed  by `$' characters.  This expansion can be prevented by
       preceding the `$' with a `\' except within `"'s where it always occurs,	and  within  `''s
       where it never occurs.  Strings quoted by ``' are interpreted later (see Command substitu-
       tion below) so `$' substitution does not occur there until later, if at	all.   A  `$'  is
       passed unchanged if followed by a blank, tab, or end-of-line.

       Input/output  redirections  are	recognized  before  variable  expansion, and are variable
       expanded separately.  Otherwise, the command name and entire argument  list  are  expanded
       together.   It  is  thus possible for the first (command) word (to this point) to generate
       more than one word, the first of which becomes the command name, and  the  rest	of  which
       become arguments.

       Unless enclosed in `"' or given the `:q' modifier the results of variable substitution may
       eventually be command and filename substituted.	Within `"', a variable whose  value  con-
       sists  of  multiple  words  expands to a (portion of a) single word, with the words of the
       variable's value separated by blanks.  When the `:q' modifier is applied to a substitution
       the  variable will expand to multiple words with each word separated by a blank and quoted
       to prevent later command or filename substitution.

       The following metasequences are provided for introducing variable values  into  the  shell
       input.  Except as noted, it is an error to reference a variable which is not set.

       ${name} Substitutes  the  words	of the value of variable name, each separated by a blank.
	       Braces insulate name from following characters which would otherwise  be  part  of
	       it.  Shell variables have names consisting of up to 20 letters and digits starting
	       with a letter.  The underscore character is considered a letter.  If name is not a
	       shell  variable,  but  is set in the environment, then that value is returned (but
	       `:' modifiers and the other forms given below are not available in this case).
	       Substitutes only the selected words from the value of name.  The selector is  sub-
	       jected to `$' substitution and may consist of a single number or two numbers sepa-
	       rated by a `-'.	The first word of a variable's value is  numbered  `1'.   If  the
	       first  number  of  a range is omitted it defaults to `1'.  If the last member of a
	       range is omitted it defaults to `$#name'.  The selector `*' selects all words.  It
	       is  not	an  error for a range to be empty if the second argument is omitted or in
       $0      Substitutes the name of the file from which command input is being read.  An error
	       occurs if the name is not known.
	       Equivalent to `$argv[number]'.
       $*      Equivalent to `$argv', which is equivalent to `$argv[*]'.

       The `:' modifiers described under History substitution, except for `:p', can be applied to
       the substitutions above.  More than one may be used.  (+) Braces may be needed to insulate
       a variable substitution from a literal colon just as with History substitution (q.v.); any
       modifiers must appear within the braces.

       The following substitutions can not be modified with `:' modifiers.

	       Substitutes the string `1' if name is set, `0' if it is not.
       $?0     Substitutes `1' if the current input filename is known, `0' if it is not.   Always
	       `0' in interactive shells.
	       Substitutes the number of words in name.
       $#      Equivalent to `$#argv'.	(+)
	       Substitutes the number of characters in name.  (+)
	       Substitutes the number of characters in $argv[number].  (+)
       $?      Equivalent to `$status'.  (+)
       $$      Substitutes the (decimal) process number of the (parent) shell.
       $!      Substitutes the (decimal) process number of the last background process started by
	       this shell.  (+)
       $_      Substitutes the command line of the last command executed.  (+)
       $<      Substitutes a line from the standard input, with no further interpretation  there-
	       after.  It can be used to read from the keyboard in a shell script.  (+) While csh
	       always quotes $<, as if it were equivalent to `$<:q', tcsh does not.  Furthermore,
	       when  tcsh  is  waiting	for  a line to be typed the user may type an interrupt to
	       interrupt the sequence into which the line is to be substituted, but csh does  not
	       allow this.

       The  editor  command  expand-variables,	normally bound to `^X-$', can be used to interac-
       tively expand individual variables.

   Command, filename and directory stack substitution
       The remaining substitutions are applied selectively to the arguments of builtin	commands.
       This means that portions of expressions which are not evaluated are not subjected to these
       expansions.  For commands which are not internal to the shell, the command name is substi-
       tuted  separately from the argument list.  This occurs very late, after input-output redi-
       rection is performed, and in a child of the main shell.

   Command substitution
       Command substitution is indicated by a command enclosed in ``'.	The output  from  such	a
       command	is  broken  into  separate words at blanks, tabs and newlines, and null words are
       discarded.  The output is variable and command substituted and put in place of the  origi-
       nal string.

       Command	substitutions  inside  double  quotes (`"') retain blanks and tabs; only newlines
       force new words.  The single final newline does not force a new word in any case.   It  is
       thus possible for a command substitution to yield only part of a word, even if the command
       outputs a complete line.

   Filename substitution
       If a word contains any of the characters `*', `?', `[' or `{' or begins with the character
       `~' it is a candidate for filename substitution, also known as ``globbing''.  This word is
       then regarded as a pattern (``glob-pattern''), and replaced with an alphabetically  sorted
       list of file names which match the pattern.

       In  matching  filenames,  the  character `.' at the beginning of a filename or immediately
       following a `/', as well as the character `/' must be matched explicitly.   The	character
       `*'  matches  any  string  of  characters,  including  the null string.	The character `?'
       matches any single character.  The sequence `[...]' matches  any  one  of  the  characters
       enclosed.   Within  `[...]',  a	pair of characters separated by `-' matches any character
       lexically between the two.

       (+) Some glob-patterns can be negated: The sequence `[^...]' matches any single	character
       not specified by the characters and/or ranges of characters in the braces.

       An entire glob-pattern can also be negated with `^':

	   > echo *
	   bang crash crunch ouch
	   > echo ^cr*
	   bang ouch

       Glob-patterns  which do not use `?', `*', or `[]' or which use `{}' or `~' (below) are not
       negated correctly.

       The metanotation `a{b,c,d}e' is a shorthand for `abe ace  ade'.	 Left-to-right	order  is
       preserved:     `/usr/source/s1/{oldls,ls}.c'	expands     to	  `/usr/source/s1/oldls.c
       /usr/source/s1/ls.c'.  The results of matches are sorted separately at a low level to pre-
       serve  this  order: `../{memo,*box}' might expand to `../memo ../box ../mbox'.  (Note that
       `memo' was not sorted with the results of matching `*box'.)  It is not an error when  this
       construct  expands  to files which do not exist, but it is possible to get an error from a
       command to which the expanded list is passed.  This construct may be nested.  As a special
       case the words `{', `}' and `{}' are passed undisturbed.

       The  character  `~'  at	the beginning of a filename refers to home directories.  Standing
       alone, i.e., `~', it expands to the invoker's home directory as reflected in the value  of
       the  home  shell  variable.  When followed by a name consisting of letters, digits and `-'
       characters the shell searches for a user with that name and substitutes their home  direc-
       tory;  thus  `~ken' might expand to `/usr/ken' and `~ken/chmach' to `/usr/ken/chmach'.  If
       the character `~' is followed by a character other than a letter or `/' or  appears  else-
       where  than  at	the  beginning of a word, it is left undisturbed.  A command like `setenv
       MANPATH /usr/man:/usr/local/man:~/lib/man' does not, therefore, do home directory  substi-
       tution as one might hope.

       It  is  an  error for a glob-pattern containing `*', `?', `[' or `~', with or without `^',
       not to match any files.	However, only one pattern in a list of glob-patterns must match a
       file  (so  that, e.g., `rm *.a *.c *.o' would fail only if there were no files in the cur-
       rent directory ending in `.a', `.c', or `.o'), and if the nonomatch shell variable is  set
       a  pattern (or list of patterns) which matches nothing is left unchanged rather than caus-
       ing an error.

       The noglob shell variable can be set to prevent filename substitution, and the expand-glob
       editor  command,  normally bound to `^X-*', can be used to interactively expand individual
       filename substitutions.

   Directory stack substitution (+)
       The directory stack is a list of directories, numbered from zero, used by the pushd,  popd
       and  dirs builtin commands (q.v.).  dirs can print, store in a file, restore and clear the
       directory stack at any time, and the savedirs and dirsfile shell variables can be  set  to
       store  the  directory stack automatically on logout and restore it on login.  The dirstack
       shell variable can be examined to see the directory stack and set to put arbitrary  direc-
       tories into the directory stack.

       The  character  `='  followed  by  one or more digits expands to an entry in the directory
       stack.  The special case `=-' expands to the last directory in the stack.  For example,

	   > dirs -v
	   0	   /usr/bin
	   1	   /usr/spool/uucp
	   2	   /usr/accts/sys
	   > echo =1
	   > echo =0/calendar
	   > echo =-

       The noglob and nonomatch shell variables and  the  expand-glob  editor  command	apply  to
       directory stack as well as filename substitutions.

   Other substitutions (+)
       There  are  several  more transformations involving filenames, not strictly related to the
       above but mentioned here for completeness.  Any filename may be expanded to  a  full  path
       when  the  symlinks  variable (q.v.) is set to `expand'.  Quoting prevents this expansion,
       and the normalize-path editor command does it on  demand.   The	normalize-command  editor
       command	expands commands in PATH into full paths on demand.  Finally, cd and pushd inter-
       pret `-' as the old working directory (equivalent to the shell variable owd).  This is not
       a  substitution	at  all, but an abbreviation recognized by only those commands.  Nonethe-
       less, it too can be prevented by quoting.

       The next three sections describe how the shell executes	commands  and  deals  with  their
       input and output.

   Simple commands, pipelines and sequences
       A  simple  command  is a sequence of words, the first of which specifies the command to be
       executed.  A series of simple commands joined by `|' characters	forms  a  pipeline.   The
       output of each command in a pipeline is connected to the input of the next.

       Simple  commands and pipelines may be joined into sequences with `;', and will be executed
       sequentially.  Commands and pipelines can also be joined into sequences with `||' or `&&',
       indicating,  as	in  the  C  language, that the second is to be executed only if the first
       fails or succeeds respectively.

       A simple command, pipeline or sequence may be placed in parentheses, `()', to form a  sim-
       ple command, which may in turn be a component of a pipeline or sequence.  A command, pipe-
       line or sequence can be executed without waiting for it to terminate by following it  with
       an `&'.

   Builtin and non-builtin command execution
       Builtin commands are executed within the shell.	If any component of a pipeline except the
       last is a builtin command, the pipeline is executed in a subshell.

       Parenthesized commands are always executed in a subshell.

	   (cd; pwd); pwd

       thus prints the home directory, leaving you where you were (printing this after	the  home
       directory), while

	   cd; pwd

       leaves  you  in the home directory.  Parenthesized commands are most often used to prevent
       cd from affecting the current shell.

       When a command to be executed is found not to be a builtin command the shell  attempts  to
       execute	the  command  via execve(2).  Each word in the variable path names a directory in
       which the shell will look for the command.  If it is given neither a -c nor a  -t  option,
       the shell hashes the names in these directories into an internal table so that it will try
       an execve(2) in only a directory where there is a possibility  that  the  command  resides
       there.	This  greatly  speeds  command	location  when	a large number of directories are
       present in the search path.  If this mechanism has been turned off (via	unhash),  if  the
       shell  was  given  a -c or -t argument or in any case for each directory component of path
       which does not begin with a `/', the shell concatenates the current working directory with
       the given command name to form a path name of a file which it then attempts to execute.

       If  the	file  has execute permissions but is not an executable to the system (i.e., it is
       neither an executable binary nor a script that specifies  its  interpreter),  then  it  is
       assumed to be a file containing shell commands and a new shell is spawned to read it.  The
       shell special alias may be set to specify an interpreter other than the shell itself.

       On systems which do not understand the `#!' script interpreter convention the shell may be
       compiled to emulate it; see the version shell variable.	If so, the shell checks the first
       line of the file to see if it is of the form `#!interpreter arg ...'.  If it is, the shell
       starts interpreter with the given args and feeds the file to it on standard input.

       The  standard  input and standard output of a command may be redirected with the following

       < name  Open file name (which is first variable, command and  filename  expanded)  as  the
	       standard input.
       << word Read  the  shell  input up to a line which is identical to word.  word is not sub-
	       jected to variable, filename or command substitution, and each input line is  com-
	       pared  to  word	before	any  substitutions are done on this input line.  Unless a
	       quoting `\', `"', `' or ``' appears in word variable and command  substitution  is
	       performed  on the intervening lines, allowing `\' to quote `$', `\' and ``'.  Com-
	       mands which are substituted have all blanks, tabs, and newlines preserved,  except
	       for the final newline which is dropped.	The resultant text is placed in an anony-
	       mous temporary file which is given to the command as standard input.
       > name
       >! name
       >& name
       >&! name
	       The file name is used as standard output.  If the file does not exist then  it  is
	       created; if the file exists, it is truncated, its previous contents being lost.

	       If the shell variable noclobber is set, then the file must not exist or be a char-
	       acter special file (e.g., a terminal or `/dev/null') or an  error  results.   This
	       helps  prevent accidental destruction of files.	In this case the `!' forms can be
	       used to suppress this check.

	       The forms involving `&' route the diagnostic output into  the  specified  file  as
	       well  as the standard output.  name is expanded in the same way as `<' input file-
	       names are.
       >> name
       >>& name
       >>! name
       >>&! name
	       Like `>', but appends output to the end of name.  If the shell variable	noclobber
	       is set, then it is an error for the file not to exist, unless one of the `!' forms
	       is given.

       A command receives the environment in which the shell  was  invoked  as	modified  by  the
       input-output  parameters and the presence of the command in a pipeline.	Thus, unlike some
       previous shells, commands run from a file of shell commands have no access to the text  of
       the  commands  by  default;  rather they receive the original standard input of the shell.
       The `<<' mechanism should be used to present inline  data.   This  permits  shell  command
       scripts	to  function  as  components  of pipelines and allows the shell to block read its
       input.  Note that the default standard input for a command run detached is not  the  empty
       file  /dev/null,  but the original standard input of the shell.	If this is a terminal and
       if the process attempts to read from the terminal, then the process  will  block  and  the
       user will be notified (see Jobs).

       Diagnostic output may be directed through a pipe with the standard output.  Simply use the
       form `|&' rather than just `|'.

       The shell cannot presently redirect diagnostic output without  also  redirecting  standard
       output,	but  `(command	>  output-file) >& error-file' is often an acceptable workaround.
       Either output-file or error-file may be `/dev/tty' to send output to the terminal.

       Having described how the shell accepts, parses and executes command lines, we now turn  to
       a variety of its useful features.

   Control flow
       The  shell contains a number of commands which can be used to regulate the flow of control
       in command files (shell scripts) and (in limited but useful  ways)  from  terminal  input.
       These commands all operate by forcing the shell to reread or skip in its input and, due to
       the implementation, restrict the placement of some of the commands.

       The foreach, switch, and while statements, as well as the  if-then-else	form  of  the  if
       statement,  require  that the major keywords appear in a single simple command on an input
       line as shown below.

       If the shell's input is not seekable, the shell buffers up input whenever a loop is  being
       read and performs seeks in this internal buffer to accomplish the rereading implied by the
       loop.  (To the extent that this	allows,  backward  gotos  will	succeed  on  non-seekable

       The if, while and exit builtin commands use expressions with a common syntax.  The expres-
       sions can include any of the operators described in the next three  sections.   Note  that
       the @ builtin command (q.v.) has its own separate syntax.

   Logical, arithmetical and comparison operators
       These operators are similar to those of C and have the same precedence.	They include

	   ||  &&  |  ^  &  ==	!=  =~	!~  <=	>=
	   <  > <<  >>	+  -  *  /  %  !  ~  (	)

       Here  the  precedence  increases  to the right, `==' `!=' `=~' and `!~', `<=' `>=' `<' and
       `>', `<<' and `>>', `+' and `-', `*' `/' and `%' being, in groups, at the same level.  The
       `=='  `!='  `=~' and `!~' operators compare their arguments as strings; all others operate
       on numbers.  The operators `=~' and `!~' are like `!=' and `==' except that the right hand
       side  is a glob-pattern (see Filename substitution) against which the left hand operand is
       matched.  This reduces the need for use of the switch builtin  command  in  shell  scripts
       when all that is really needed is pattern matching.

       Strings	which begin with `0' are considered octal numbers.  Null or missing arguments are
       considered `0'.	The results of all expressions are strings, which represent decimal  num-
       bers.   It  is important to note that no two components of an expression can appear in the
       same word; except when adjacent to components of expressions which are syntactically  sig-
       nificant to the parser (`&' `|' `<' `>' `(' `)') they should be surrounded by spaces.

   Command exit status
       Commands  can  be executed in expressions and their exit status returned by enclosing them
       in braces (`{}').  Remember that the braces should be separated from the words of the com-
       mand  by  spaces.   Command  executions succeed, returning true, i.e., `1', if the command
       exits with status 0, otherwise they fail, returning false, i.e., `0'.   If  more  detailed
       status  information  is required then the command should be executed outside of an expres-
       sion and the status shell variable examined.

   File inquiry operators
       Some of these operators perform true/false tests on files and related objects.	They  are
       of the form -op file, where op is one of

	   r   Read access
	   w   Write access
	   x   Execute access
	   X   Executable in the path or shell builtin, e.g., `-X ls' and `-X ls-F' are generally
	       true, but `-X /bin/ls' is not (+)
	   e   Existence
	   o   Ownership
	   z   Zero size
	   s   Non-zero size (+)
	   f   Plain file
	   d   Directory
	   l   Symbolic link (+) *
	   b   Block special file (+)
	   c   Character special file (+)
	   p   Named pipe (fifo) (+) *
	   S   Socket special file (+) *
	   u   Set-user-ID bit is set (+)
	   g   Set-group-ID bit is set (+)
	   k   Sticky bit is set (+)
	   t   file (which must be a digit) is an open file descriptor for a terminal device (+)
	   R   Has been migrated (convex only) (+)
	   L   Applies subsequent operators in a multiple-operator test to a symbolic link rather
	       than to the file to which the link points (+) *

       file is command and filename expanded and then tested to see if it has the specified rela-
       tionship to the real user.  If file does not exist or is inaccessible or, for  the  opera-
       tors  indicated	by  `*', if the specified file type does not exist on the current system,
       then all enquiries return false, i.e., `0'.

       These operators may be combined for conciseness: `-xy file' is equivalent to `-x  file  &&
       -y  file'.   (+)  For example, `-fx' is true (returns `1') for plain executable files, but
       not for directories.

       L may be used in a multiple-operator test to apply subsequent operators to a symbolic link
       rather  than  to the file to which the link points.  For example, `-lLo' is true for links
       owned by the invoking user.  Lr, Lw and Lx are always true for links and  false	for  non-
       links.	L  has	a  different  meaning when it is the last operator in a multiple-operator
       test; see below.

       It is possible but not useful, and sometimes misleading, to combine operators which expect
       file  to  be a file with operators which do not, (e.g., X and t).  Following L with a non-
       file operator can lead to particularly strange results.

       Other operators return other information, i.e., not just `0' or `1'.  (+)  They	have  the
       same format as before; op may be one of

	   A	   Last file access time, as the number of seconds since the epoch
	   A:	   Like A, but in timestamp format, e.g., `Fri May 14 16:36:10 1993'
	   M	   Last file modification time
	   M:	   Like M, but in timestamp format
	   C	   Last inode modification time
	   C:	   Like C, but in timestamp format
	   D	   Device number
	   I	   Inode number
	   F	   Composite file identifier, in the form device:inode
	   L	   The name of the file pointed to by a symbolic link
	   N	   Number of (hard) links
	   P	   Permissions, in octal, without leading zero
	   P:	   Like P, with leading zero
	   Pmode   Equivalent  to  `-P	file  &  mode', e.g., `-P22 file' returns `22' if file is
		   writable by group and other, `20' if by group only, and `0' if by neither
	   Pmode:  Like Pmode:, with leading zero
	   U	   Numeric userid
	   U:	   Username, or the numeric userid if the username is unknown
	   G	   Numeric groupid
	   G:	   Groupname, or the numeric groupid if the groupname is unknown
	   Z	   Size, in bytes

       Only one of these operators may appear in a multiple-operator test, and	it  must  be  the
       last.  Note that L has a different meaning at the end of and elsewhere in a multiple-oper-
       ator test.  Because `0' is a valid return value for many of these operators, they  do  not
       return `0' when they fail: most return `-1', and F returns `:'.

       If  the	shell is compiled with POSIX defined (see the version shell variable), the result
       of a file inquiry is based on the permission bits of the file and not on the result of the
       access(2)  system  call.  For example, if one tests a file with -w whose permissions would
       ordinarily allow writing but which is on a file system mounted read-only,  the  test  will
       succeed in a POSIX shell but fail in a non-POSIX shell.

       File inquiry operators can also be evaluated with the filetest builtin command (q.v.) (+).

       The  shell associates a job with each pipeline.	It keeps a table of current jobs, printed
       by the jobs command, and assigns them small integer numbers.  When a job is started  asyn-
       chronously with `&', the shell prints a line which looks like

	   [1] 1234

       indicating  that  the  job  which  was started asynchronously was job number 1 and had one
       (top-level) process, whose process id was 1234.

       If you are running a job and wish to do something else you may hit the suspend  key  (usu-
       ally  `^Z'),  which  sends a STOP signal to the current job.  The shell will then normally
       indicate that the job has been `Suspended' and print  another  prompt.	If  the  listjobs
       shell variable is set, all jobs will be listed like the jobs builtin command; if it is set
       to `long' the listing will be in long format, like `jobs -l'.  You can then manipulate the
       state  of  the suspended job.  You can put it in the ``background'' with the bg command or
       run some other commands and eventually bring the job back into the ``foreground'' with fg.
       (See  also the run-fg-editor editor command.)  A `^Z' takes effect immediately and is like
       an interrupt in that pending output and unread input are discarded when it is typed.   The
       wait builtin command causes the shell to wait for all background jobs to complete.

       The `^]' key sends a delayed suspend signal, which does not generate a STOP signal until a
       program attempts to read(2) it, to the current job.  This can usefully be typed ahead when
       you  have  prepared some commands for a job which you wish to stop after it has read them.
       The `^Y' key performs this function in csh(1); in tcsh, `^Y' is an editing command.  (+)

       A job being run in the background stops if it tries to read from the terminal.  Background
       jobs  are  normally allowed to produce output, but this can be disabled by giving the com-
       mand `stty tostop'.  If you set this tty option, then background jobs will stop when  they
       try to produce output like they do when they try to read input.

       There  are several ways to refer to jobs in the shell.  The character `%' introduces a job
       name.  If you wish to refer to job number 1, you can name it as `%1'.  Just naming  a  job
       brings  it to the foreground; thus `%1' is a synonym for `fg %1', bringing job 1 back into
       the foreground.	Similarly, saying `%1 &' resumes job 1 in the background, just	like  `bg
       %1'.  A job can also be named by an unambiguous prefix of the string typed in to start it:
       `%ex' would normally restart a suspended ex(1) job, if there were only one  suspended  job
       whose name began with the string `ex'.  It is also possible to say `%?string' to specify a
       job whose text contains string, if there is only one such job.

       The shell maintains a notion of the current and previous jobs.  In  output  pertaining  to
       jobs, the current job is marked with a `+' and the previous job with a `-'.  The abbrevia-
       tions `%+', `%', and (by analogy with the syntax of the history mechanism) `%%' all  refer
       to the current job, and `%-' refers to the previous job.

       The  job  control mechanism requires that the stty(1) option `new' be set on some systems.
       It is an artifact from a `new' implementation of the tty driver which allows generation of
       interrupt  characters  from  the keyboard to tell jobs to stop.	See stty(1) and the setty
       builtin command for details on setting options in the new tty driver.

   Status reporting
       The shell learns immediately whenever a process changes state.  It  normally  informs  you
       whenever  a  job  becomes  blocked so that no further progress is possible, but only right
       before it prints a prompt.  This is done so that it does not otherwise disturb your  work.
       If,  however,  you set the shell variable notify, the shell will notify you immediately of
       changes of status in background jobs.  There is also a shell command notify which marks	a
       single process so that its status changes will be immediately reported.	By default notify
       marks the current process; simply say `notify' after starting a background job to mark it.

       When you try to leave the shell while jobs are stopped, you will be warned that `You  have
       stopped jobs.' You may use the jobs command to see what they are.  If you do this or imme-
       diately try to exit again, the shell will not warn you a second time,  and  the	suspended
       jobs will be terminated.

   Automatic, periodic and timed events (+)
       There  are  various  ways  to run commands and take other actions automatically at various
       times in the ``life cycle'' of the shell.  They are  summarized	here,  and  described  in
       detail  under  the  appropriate	Builtin  commands,  Special  shell  variables and Special

       The sched builtin command puts commands in a scheduled-event list, to be executed  by  the
       shell at a given time.

       The  beepcmd,  cwdcmd,  periodic,  precmd, postcmd, and jobcmd Special aliases can be set,
       respectively, to execute commands when the shell wants to ring the bell, when the  working
       directory  changes,  every  tperiod  minutes, before each prompt, before each command gets
       executed, after each command gets executed, and when a job is started or is  brought  into
       the foreground.

       The autologout shell variable can be set to log out or lock the shell after a given number
       of minutes of inactivity.

       The mail shell variable can be set to check for new mail periodically.

       The printexitvalue shell variable can be set to print the exit status  of  commands  which
       exit with a status other than zero.

       The  rmstar  shell  variable  can be set to ask the user, when `rm *' is typed, if that is
       really what was meant.

       The time shell variable can be set to execute the time builtin command after  the  comple-
       tion of any process that takes more than a given number of CPU seconds.

       The  watch and who shell variables can be set to report when selected users log in or out,
       and the log builtin command reports on those users at any time.

   Native Language System support (+)
       The shell is eight bit clean (if so compiled; see the version  shell  variable)	and  thus
       supports character sets needing this capability.  NLS support differs depending on whether
       or not the shell was compiled to use the system's NLS (again,  see  version).   In  either
       case,  7-bit ASCII is the default for character classification (e.g., which characters are
       printable) and sorting, and changing the LANG or LC_CTYPE environment variables	causes	a
       check for possible changes in these respects.

       When  using the system's NLS, the setlocale(3) function is called to determine appropriate
       character classification and sorting.  This  function  typically  examines  the	LANG  and
       LC_CTYPE  environment  variables;  refer  to the system documentation for further details.
       When not using the system's NLS, the shell simulates it by assuming that  the  ISO  8859-1
       character  set is used whenever either of the LANG and LC_CTYPE variables are set, regard-
       less of their values.  Sorting is not affected for the simulated NLS.

       In addition, with both real and simulated NLS,  all  printable  characters  in  the  range
       \200-\377,  i.e.,  those  that  have  M-char  bindings, are automatically rebound to self-
       insert-command.	The corresponding binding for the escape-char sequence, if any,  is  left
       alone.	These  characters  are	not  rebound if the NOREBIND environment variable is set.
       This may be useful for the simulated NLS or a primitive real NLS which  assumes	full  ISO
       8859-1.	 Otherwise,  all  M-char  bindings in the range \240-\377 are effectively undone.
       Explicitly rebinding the relevant keys with bindkey is of course still possible.

       Unknown characters (i.e., those that are neither printable  nor	control  characters)  are
       printed	in  the format \nnn.  If the tty is not in 8 bit mode, other 8 bit characters are
       printed by converting them to ASCII and using standout mode.  The shell never changes  the
       7/8 bit mode of the tty and tracks user-initiated changes of 7/8 bit mode.  NLS users (or,
       for that matter, those who want to use a meta key) may need to explicitly set the tty in 8
       bit mode through the appropriate stty(1) command in, e.g., the ~/.login file.

   OS variant support (+)
       A  number of new builtin commands are provided to support features in particular operating
       systems.  All are described in detail in the Builtin commands section.

       On systems that support TCF (aix-ibm370, aix-ps2), getspath and setspath get and  set  the
       system  execution  path, getxvers and setxvers get and set the experimental version prefix
       and migrate migrates processes between sites.  The jobs builtin prints the site	on  which
       each job is executing.

       Under  Domain/OS, inlib adds shared libraries to the current environment, rootnode changes
       the rootnode and ver changes the systype.

       Under Mach, setpath is equivalent to Mach's setpath(1).

       Under Masscomp/RTU and Harris CX/UX, universe sets the universe.

       Under Harris CX/UX, ucb or att runs a command under the specified universe.

       Under Convex/OS, warp prints or sets the universe.

       The VENDOR, OSTYPE and MACHTYPE environment variables indicate  respectively  the  vendor,
       operating system and machine type (microprocessor class or machine model) of the system on
       which the shell thinks it is running.  These are particularly useful  when  sharing  one's
       home directory between several types of machines; one can, for example,

	   set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)

       in  one's ~/.login and put executables compiled for each machine in the appropriate direc-

       The version shell variable indicates what options were chosen when the shell was compiled.

       Note also the newgrp builtin, the afsuser and echo_style shell variables and  the  system-
       dependent locations of the shell's input files (see FILES).

   Signal handling
       Login  shells  ignore  interrupts when reading the file ~/.logout.  The shell ignores quit
       signals unless started with -q.	Login shells catch the terminate  signal,  but	non-login
       shells  inherit	the terminate behavior from their parents.  Other signals have the values
       which the shell inherited from its parent.

       In shell scripts, the shell's handling of interrupt and	terminate  signals  can  be  con-
       trolled with onintr, and its handling of hangups can be controlled with hup and nohup.

       The shell exits on a hangup (see also the logout shell variable).  By default, the shell's
       children do too, but the shell does not send them a hangup when it  exits.   hup  arranges
       for  the shell to send a hangup to a child when it exits, and nohup sets a child to ignore

   Terminal management (+)
       The shell uses three different sets of terminal (``tty'') modes: `edit', used  when  edit-
       ing,  `quote',  used  when  quoting literal characters, and `execute', used when executing
       commands.  The shell holds some settings in each mode constant, so  commands  which  leave
       the  tty  in  a	confused  state  do not interfere with the shell.  The shell also matches
       changes in the speed and padding of the tty.  The list of tty modes that are kept constant
       can  be	examined and modified with the setty builtin.  Note that although the editor uses
       CBREAK mode (or its equivalent), it takes typed-ahead characters anyway.

       The echotc, settc and telltc commands can be used to manipulate and debug  terminal  capa-
       bilities from the command line.

       On  systems  that support SIGWINCH or SIGWINDOW, the shell adapts to window resizing auto-
       matically and adjusts the environment variables LINES and COLUMNS if set.  If the environ-
       ment  variable  TERMCAP contains li# and co# fields, the shell adjusts them to reflect the
       new window size.

       The next sections of this manual describe all of the available Builtin  commands,  Special
       aliases and Special shell variables.

   Builtin commands
       %job    A synonym for the fg builtin command.

       %job &  A synonym for the bg builtin command.

       :       Does nothing, successfully.

       @ name = expr
       @ name[index] = expr
       @ name++|--
       @ name[index]++|--
	       The first form prints the values of all shell variables.

	       The  second  form  assigns  the value of expr to name.  The third form assigns the
	       value of expr to the index'th component of name; both name and its index'th compo-
	       nent must already exist.

	       expr  may  contain  the	operators `*', `+', etc., as in C.  If expr contains `<',
	       `>', `&' or `' then at least that part of expr must be placed within  `()'.   Note
	       that the syntax of expr has nothing to do with that described under Expressions.

	       The  fourth  and  fifth	forms  increment  (`++')  or decrement (`--') name or its
	       index'th component.

	       The space between `@' and name is required.  The spaces between name and  `='  and
	       between	`='  and expr are optional.  Components of expr must be separated by spa-

       alias [name [wordlist]]
	       Without arguments, prints all aliases.  With name,  prints  the	alias  for  name.
	       With  name  and wordlist, assigns wordlist as the alias of name.  wordlist is com-
	       mand and filename substituted.  name may not be `alias' or  `unalias'.	See  also
	       the unalias builtin command.

       alloc   Shows  the  amount of dynamic memory acquired, broken down into used and free mem-
	       ory.  With an argument shows the number of free and used blocks in each size cate-
	       gory.   The  categories	start  at size 8 and double at each step.  This command's
	       output may vary across system types, because systems other than the VAX may use	a
	       different memory allocator.

       bg [%job ...]
	       Puts  the  specified  jobs (or, without arguments, the current job) into the back-
	       ground, continuing each if it is stopped.  job may be a number, a string, `', `%',
	       `+' or `-' as described under Jobs.

       bindkey [-l|-d|-e|-v|-u] (+)
       bindkey [-a] [-b] [-k] [-r] [--] key (+)
       bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
	       Without	options,  the  first  form lists all bound keys and the editor command to
	       which each is bound, the second form lists the editor  command  to  which  key  is
	       bound  and  the	third  form  binds  the  editor  command command to key.  Options

	       -l  Lists all editor commands and a short description of each.
	       -d  Binds all keys to the standard bindings for the default editor.
	       -e  Binds all keys to the standard GNU Emacs-like bindings.
	       -v  Binds all keys to the standard vi(1)-like bindings.
	       -a  Lists or changes key-bindings in the alternative key map.  This is the key map
		   used in vi command mode.
	       -b  key	is  interpreted as a control character written ^character (e.g., `^A') or
		   C-character (e.g., `C-A'), a meta character written M-character (e.g., `M-A'),
		   a  function key written F-string (e.g., `F-string'), or an extended prefix key
		   written X-character (e.g., `X-A').
	       -k  key is interpreted as a symbolic arrow key name, which may be one  of  `down',
		   `up', `left' or `right'.
	       -r  Removes  key's  binding.   Be careful: `bindkey -r' does not bind key to self-
		   insert-command (q.v.), it unbinds key completely.
	       -c  command is interpreted as a builtin or external command instead of  an  editor
	       -s  command is taken as a literal string and treated as terminal input when key is
		   typed.  Bound keys in command are themselves reinterpreted, and this continues
		   for ten levels of interpretation.
	       --  Forces  a  break from option processing, so the next word is taken as key even
		   if it begins with '-'.
	       -u (or any invalid option)
		   Prints a usage message.

	       key may be a single character or a string.  If a command is bound to a string, the
	       first  character  of the string is bound to sequence-lead-in and the entire string
	       is bound to the command.

	       Control characters in key can be literal (they can be typed by preceding them with
	       the editor command quoted-insert, normally bound to `^V') or written caret-charac-
	       ter style, e.g., `^A'.  Delete is written `^?'  (caret-question	mark).	 key  and
	       command	can  contain  backslashed  escape  sequences  (in  the	style of System V
	       echo(1)) as follows:

		   \a	   Bell
		   \b	   Backspace
		   \e	   Escape
		   \f	   Form feed
		   \n	   Newline
		   \r	   Carriage return
		   \t	   Horizontal tab
		   \v	   Vertical tab
		   \nnn    The ASCII character corresponding to the octal number nnn

	       `\' nullifies the special meaning of the  following  character,	if  it	has  any,
	       notably `\' and `^'.

       break   Causes  execution  to  resume  after  the  end of the nearest enclosing foreach or
	       while.  The remaining commands on the  current  line  are  executed.   Multi-level
	       breaks are thus possible by writing them all on one line.

       breaksw Causes a break from a switch, resuming after the endsw.

       builtins (+)
	       Prints the names of all builtin commands.

       bye (+) A synonym for the logout builtin command.  Available only if the shell was so com-
	       piled; see the version shell variable.

       case label:
	       A label in a switch statement as discussed below.

       cd [-p] [-l] [-n|-v] [name]
	       If a directory name is given, changes the shell's working directory to  name.   If
	       not,  changes  to  home.  If name is `-' it is interpreted as the previous working
	       directory (see Other substitutions).  (+) If name is not  a  subdirectory  of  the
	       current	directory (and does not begin with `/', `./' or `../'), each component of
	       the variable cdpath is checked to see if it has a subdirectory name.  Finally,  if
	       all else fails but name is a shell variable whose value begins with `/', then this
	       is tried to see if it is a directory.

	       With -p, prints the final directory stack, just like dirs.   The  -l,  -n  and  -v
	       flags have the same effect on cd as on dirs, and they imply -p.	(+)

	       See also the implicitcd shell variable.

       chdir   A synonym for the cd builtin command.

       complete [command [word/pattern/list[:select]/[[suffix]/] ...]] (+)
	       Without	arguments,  lists  all	completions.  With command, lists completions for
	       command.  With command and word etc., defines completions.

	       command may be a full command name or a glob-pattern (see Filename  substitution).
	       It can begin with `-' to indicate that completion should be used only when command
	       is ambiguous.

	       word specifies which word relative to the current word is to be completed, and may
	       be one of the following:

		   c   Current-word  completion.   pattern is a glob-pattern which must match the
		       beginning of the current word on the command  line.   pattern  is  ignored
		       when completing the current word.
		   C   Like c, but includes pattern when completing the current word.
		   n   Next-word  completion.	pattern  is  a	glob-pattern which must match the
		       beginning of the previous word on the command line.
		   N   Like n, but must match the beginning of the word two  before  the  current
		   p   Position-dependent  completion.	pattern is a numeric range, with the same
		       syntax used to index shell variables, which must include the current word.

	       list, the list of possible completions, may be one of the following:

		   a	   Aliases
		   b	   Bindings (editor commands)
		   c	   Commands (builtin or external commands)
		   C	   External commands which begin with the supplied path prefix
		   d	   Directories
		   D	   Directories which begin with the supplied path prefix
		   e	   Environment variables
		   f	   Filenames
		   F	   Filenames which begin with the supplied path prefix
		   g	   Groupnames
		   j	   Jobs
		   l	   Limits
		   n	   Nothing
		   s	   Shell variables
		   S	   Signals
		   t	   Plain (``text'') files
		   T	   Plain (``text'') files which begin with the supplied path prefix
		   v	   Any variables
		   u	   Usernames
		   x	   Like n, but prints select when list-choices is used.
		   X	   Completions
		   $var    Words from the variable var
		   (...)   Words from the given list
		   `...`   Words from the output of command

	       select is an optional glob-pattern.  If given, words from  only	list  that  match
	       select  are  considered and the fignore shell variable is ignored.  The last three
	       types of completion may not have a  select  pattern,  and  x  uses  select  as  an
	       explanatory message when the list-choices editor command is used.

	       suffix  is a single character to be appended to a successful completion.  If null,
	       no character is appended.  If omitted (in which case the fourth delimiter can also
	       be omitted), a slash is appended to directories and a space to other words.

	       Now  for  some  examples.   Some  commands  take only directories as arguments, so
	       there's no point completing plain files.

		   > complete cd 'p/1/d/'

	       completes only the first word following `cd' (`p/1')  with  a  directory.   p-type
	       completion can also be used to narrow down command completion:

		   > co[^D]
		   complete compress
		   > complete -co* 'p/0/(compress)/'
		   > co[^D]
		   > compress

	       This  completion  completes commands (words in position 0, `p/0') which begin with
	       `co' (thus matching `co*') to `compress' (the only word in the list).  The leading
	       `-' indicates that this completion is to be used with only ambiguous commands.

		   > complete find 'n/-user/u/'

	       is  an  example	of  n-type completion.	Any word following `find' and immediately
	       following `-user' is completed from the list of users.

		   > complete cc 'c/-I/d/'

	       demonstrates c-type completion.	Any word following `cc' and beginning  with  `-I'
	       is  completed  as a directory.  `-I' is not taken as part of the directory because
	       we used lowercase c.

	       Different lists are useful with different commands.

		   > complete alias 'p/1/a/'
		   > complete man 'p/*/c/'
		   > complete set 'p/1/s/'
		   > complete true 'p/1/x:Truth has no options./'

	       These complete words following `alias' with  aliases,  `man'  with  commands,  and
	       `set'  with  shell  variables.  `true' doesn't have any options, so x does nothing
	       when completion is attempted and prints `Truth has no  options.'  when  completion
	       choices are listed.

	       Note  that  the	man example, and several other examples below, could just as well
	       have used 'c/*' or 'n/*' as 'p/*'.

	       Words can be completed from a variable evaluated at completion time,

		   > complete ftp 'p/1/$hostnames/'
		   > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu)
		   > ftp [^D]
		   rtfm.mit.edu tesla.ee.cornell.edu
		   > ftp [^C]
		   > set hostnames = (rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net)
		   > ftp [^D]
		   rtfm.mit.edu tesla.ee.cornell.edu uunet.uu.net

	       or from a command run at completion time:

		   > complete kill 'p/*/`ps | awk \{print\ \$1\}`/'
		   > kill -9 [^D]
		   23113 23377 23380 23406 23429 23529 23530 PID

	       Note that the complete command does not itself quote its arguments, so the braces,
	       space and `$' in `{print $1}' must be quoted explicitly.

	       One command can have multiple completions:

		   > complete dbx 'p/2/(core)/' 'p/*/c/'

	       completes  the  second  argument to `dbx' with the word `core' and all other argu-
	       ments with commands.  Note that the positional completion is specified before  the
	       next-word  completion.	Because  completions are evaluated from left to right, if
	       the next-word completion were specified first it would always match and the  posi-
	       tional completion would never be executed.  This is a common mistake when defining
	       a completion.

	       The select pattern is useful when a command takes files with only particular forms
	       as arguments.  For example,

		   > complete cc 'p/*/f:*.[cao]/'

	       completes  `cc' arguments to files ending in only `.c', `.a', or `.o'.  select can
	       also exclude files, using negation of a glob-pattern as described  under  Filename
	       substitution.  One might use

		   > complete rm 'p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/'

	       to  exclude precious source code from `rm' completion.  Of course, one could still
	       type excluded names manually or override the completion mechanism using	the  com-
	       plete-word-raw or list-choices-raw editor commands (q.v.).

	       The  `C',  `D', `F' and `T' lists are like `c', `d', `f' and `t' respectively, but
	       they use the select argument in a different way: to restrict completion	to  files
	       beginning  with	a particular path prefix.  For example, the Elm mail program uses
	       `=' as an abbreviation for one's mail directory.  One might use

		   > complete elm c@=@F:$HOME/Mail/@

	       to complete `elm -f =' as if it were `elm -f ~/Mail/'.	Note  that  we	used  `@'
	       instead	of  `/'  to avoid confusion with the select argument, and we used `$HOME'
	       instead of `~' because home directory substitution works at only the beginning  of
	       a word.

	       suffix  is  used to add a nonstandard suffix (not space or `/' for directories) to
	       completed words.

		   > complete finger 'c/*@/$hostnames/' 'p/1/u/@'

	       completes arguments to `finger' from the list of users, appends an `@',	and  then
	       completes  after  the  `@' from the `hostnames' variable.  Note again the order in
	       which the completions are specified.

	       Finally, here's a complex example for inspiration:

		   > complete find \
		   'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \
		   'n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \
		   'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \
		   'n/-type/(b c d f l p s)/' \
		   'c/-/(name newer cpio ncpio exec ok user \
		   group fstype type atime ctime depth inum \
		   ls mtime nogroup nouser perm print prune \
		   size xdev)/' \

	       This completes words following `-name', `-newer', `-cpio'  or  `ncpio'  (note  the
	       pattern	which  matches	both)  to files, words following `-exec' or `-ok' to com-
	       mands, words following `user' and `group' to users  and	groups	respectively  and
	       words  following `-fstype' or `-type' to members of the given lists.  It also com-
	       pletes the switches themselves from the given list (note the use of c-type comple-
	       tion) and completes anything not otherwise completed to a directory.  Whew.

	       Remember  that programmed completions are ignored if the word being completed is a
	       tilde substitution (beginning with `~') or a variable (beginning with `$').   com-
	       plete  is an experimental feature, and the syntax may change in future versions of
	       the shell.  See also the uncomplete builtin command.

	       Continues execution of the nearest enclosing while or foreach.  The  rest  of  the
	       commands on the current line are executed.

	       Labels  the  default  case  in  a switch statement.  It should come after all case

       dirs [-l] [-n|-v]
       dirs -S|-L [filename] (+)
       dirs -c (+)
	       The first form prints the directory stack.  The top of the stack is  at	the  left
	       and  the  first	directory in the stack is the current directory.  With -l, `~' or
	       `~name' in the output is expanded explicitly to home or the pathname of	the  home
	       directory  for  user name.  (+) With -n, entries are wrapped before they reach the
	       edge of the screen.  (+) With -v, entries are printed one per  line,  preceded  by
	       their stack positions.  (+) If more than one of -n or -v is given, -v takes prece-
	       dence.  -p is accepted but does nothing.

	       With -S, the second form saves the directory stack to filename as a series  of  cd
	       and  pushd  commands.   With -L, the shell sources filename, which is presumably a
	       directory stack file saved by the -S option or the savedirs mechanism.  In  either
	       case, dirsfile is used if filename is not given and ~/.cshdirs is used if dirsfile
	       is unset.

	       Note that login shells do the equivalent of `dirs -L' on startup and, if  savedirs
	       is  set,  `dirs	-S'  before  exiting.  Because only ~/.tcshrc is normally sourced
	       before ~/.cshdirs, dirsfile should be set in ~/.tcshrc rather than ~/.login.

	       The last form clears the directory stack.

       echo [-n] word ...
	       Writes each word to the shell's standard output, separated by  spaces  and  termi-
	       nated  with  a  newline.   The echo_style shell variable may be set to emulate (or
	       not) the flags and escape sequences of the BSD and/or System V versions	of  echo;
	       see echo(1).

       echotc [-sv] arg ... (+)
	       Exercises  the  terminal  capabilities  (see  termcap(5))  in  args.  For example,
	       'echotc home' sends the cursor to the home position, 'echotc cm 3 10' sends it  to
	       column  3  and row 10, and 'echotc ts 0; echo "This is a test."; echotc fs' prints
	       "This is a test."  in the status line.

	       If arg is 'baud', 'cols', 'lines', 'meta' or 'tabs',  prints  the  value  of  that
	       capability  ("yes" or "no" indicating that the terminal does or does not have that
	       capability).  One might use this to make the output from a shell script less  ver-
	       bose  on  slow  terminals,  or  limit command output to the number of lines on the

		   > set history=`echotc lines`
		   > @ history--

	       Termcap strings may contain wildcards which will not echo correctly.   One  should
	       use  double  quotes when setting a shell variable to a terminal capability string,
	       as in the following example that places the date in the status line:

		   > set tosl="`echotc ts 0`"
		   > set frsl="`echotc fs`"
		   > echo -n "$tosl";date; echo -n "$frsl"

	       With -s, nonexistent capabilities return the empty string rather than  causing  an
	       error.  With -v, messages are verbose.

       endsw   See the description of the foreach, if, switch, and while statements below.

       eval arg ...
	       Treats  the  arguments as input to the shell and executes the resulting command(s)
	       in the context of the current shell.  This is usually  used  to	execute  commands
	       generated  as  the  result  of  command	or variable substitution, because parsing
	       occurs before these substitutions.  See tset(1) for a sample use of eval.

       exec command
	       Executes the specified command in place of the current shell.

       exit [expr]
	       The shell exits either with the value of the specified  expr  (an  expression,  as
	       described  under Expressions) or, without expr, with the value of the status vari-

       fg [%job ...]
	       Brings the specified jobs (or, without arguments, the current job) into the  fore-
	       ground, continuing each if it is stopped.  job may be a number, a string, `', `%',
	       `+' or `-' as described under Jobs.  See also the run-fg-editor editor command.

       filetest -op file ... (+)
	       Applies op (which is a file inquiry operator as described under File inquiry oper-
	       ators) to each file and returns the results as a space-separated list.

       foreach name (wordlist)
       end     Successively  sets  the	variable name to each member of wordlist and executes the
	       sequence of commands between this command and the matching end.	(Both foreach and
	       end  must  appear  alone  on separate lines.)  The builtin command continue may be
	       used to continue the loop prematurely and the builtin command break  to	terminate
	       it  prematurely.   When	this  command is read from the terminal, the loop is read
	       once prompting with `foreach? ' (or prompt2) before any statements in the loop are
	       executed.   If  you make a mistake typing in a loop at the terminal you can rub it

       getspath (+)
	       Prints the system execution path.  (TCF only)

       getxvers (+)
	       Prints the experimental version prefix.	(TCF only)

       glob wordlist
	       Like echo, but no `\' escapes are recognized and words are delimited by null char-
	       acters in the output.  Useful for programs which wish to use the shell to filename
	       expand a list of words.

       goto word
	       word is filename and command-substituted to yield a string of  the  form  `label'.
	       The  shell  rewinds its input as much as possible, searches for a line of the form
	       `label:', possibly preceded by blanks or tabs, and continues execution after  that

	       Prints a statistics line indicating how effective the internal hash table has been
	       at locating commands (and avoiding exec's).  An exec is attempted for each  compo-
	       nent  of  the  path  where the hash function indicates a possible hit, and in each
	       component which does not begin with a `/'.

	       On machines without vfork(2), prints only the number and size of hash buckets.

       history [-hTr] [n]
       history -S|-L|-M [filename] (+)
       history -c (+)
	       The first form prints the history event list.  If n  is	given  only  the  n  most
	       recent  events are printed or saved.  With -h, the history list is printed without
	       leading numbers.  If -T is specified, timestamps are printed also in comment form.
	       (This  can  be  used  to  produce  files suitable for loading with 'history -L' or
	       'source -h'.)  With -r, the order of printing is most  recent  first  rather  than
	       oldest first.

	       With -S, the second form saves the history list to filename.  If the first word of
	       the savehist shell variable is set to a number, at most that many lines are saved.
	       If  the second word of savehist is set to `merge', the history list is merged with
	       the existing history file instead of replacing it (if there is one) and sorted  by
	       time  stamp.   (+) Merging is intended for an environment like the X Window System
	       with several shells in simultaneous use.  Currently  it	succeeds  only	when  the
	       shells quit nicely one after another.

	       With  -L,  the shell appends filename, which is presumably a history list saved by
	       the -S option or the savehist mechanism, to the history list.  -M is like -L,  but
	       the contents of filename are merged into the history list and sorted by timestamp.
	       In either case, histfile is used if filename is not given and ~/.history  is  used
	       if  histfile  is  unset.   `history -L' is exactly like 'source -h' except that it
	       does not require a filename.

	       Note that login shells do the equivalent of `history -L' on startup and, if  save-
	       hist  is  set,  `history  -S'  before exiting.  Because only ~/.tcshrc is normally
	       sourced before ~/.history,  histfile  should  be  set  in  ~/.tcshrc  rather  than

	       If  histlit  is	set, the first and second forms print and save the literal (unex-
	       panded) form of the history list.

	       The last form clears the history list.

       hup [command] (+)
	       With command, runs command such that it will exit on a hangup signal and  arranges
	       for the shell to send it a hangup signal when the shell exits.  Note that commands
	       may set their own response  to  hangups,  overriding  hup.   Without  an  argument
	       (allowed  in  only  a  shell script), causes the shell to exit on a hangup for the
	       remainder of the script.  See also Signal handling and the nohup builtin command.

       if (expr) command
	       If expr (an expression, as described under Expressions) evaluates true, then  com-
	       mand  is  executed.   Variable  substitution on command happens early, at the same
	       time it does for the rest of the if command.  command must be  a  simple  command,
	       not  an	alias, a pipeline, a command list or a parenthesized command list, but it
	       may have arguments.  Input/output redirection occurs even if  expr  is  false  and
	       command is thus not executed; this is a bug.

       if (expr) then
       else if (expr2) then
       endif   If  the	specified  expr is true then the commands to the first else are executed;
	       otherwise if expr2 is true then the commands to the second else are executed, etc.
	       Any number of else-if pairs are possible; only one endif is needed.  The else part
	       is likewise optional.  (The words else and endif must appear at the  beginning  of
	       input lines; the if must appear alone on its input line or after an else.)

       inlib shared-library ... (+)
	       Adds  each shared-library to the current environment.  There is no way to remove a
	       shared library.	(Domain/OS only)

       jobs [-l]
	       Lists the active jobs.  With -l, lists process  IDs  in	addition  to  the  normal
	       information.  On TCF systems, prints the site on which each job is executing.

       kill [-s signal] %job|pid ...
       kill -l The  first  and second forms sends the specified signal (or, if none is given, the
	       TERM (terminate) signal) to the specified jobs or processes.  job may be a number,
	       a  string,  `', `%', `+' or `-' as described under Jobs.  Signals are either given
	       by number or by name (as given in /usr/include/signal.h, stripped  of  the  prefix
	       `SIG').	There is no default job; saying just `kill' does not send a signal to the
	       current job.  If the signal being sent is TERM (terminate) or HUP  (hangup),  then
	       the job or process is sent a CONT (continue) signal as well.  The third form lists
	       the signal names.

       limit [-h] [resource [maximum-use]]
	       Limits the consumption by the current process and each process it creates  to  not
	       individually  exceed  maximum-use on the specified resource.  If no maximum-use is
	       given, then the current limit is printed; if no resource is given, then all  limi-
	       tations	are  given.  If the -h flag is given, the hard limits are used instead of
	       the current limits.  The hard limits impose a ceiling on the values of the current
	       limits.	 Only  the  super-user may raise the hard limits, but a user may lower or
	       raise the current limits within the legal range.

	       Controllable resources currently include (if supported by the OS):

		      the maximum number of cpu-seconds to be used by each process

		      the largest single file which can be created

		      the maximum growth of the data+stack region via sbrk(2) beyond the  end  of
		      the program text

		      the maximum size of the automatically-extended stack region

		      the size of the largest core dump that will be created

		      the maximum amount of physical memory a process may have allocated to it at
		      a given time

	       descriptors or openfiles
		      the maximum number of open files for this process

		      the maximum number of threads for this process

		      the maximum size which a process may lock into memory using mlock(2)

		      the maximum number of simultaneous processes for this user id

	       sbsize the maximum size of socket buffer usage for this user

	       maximum-use may be given as a (floating point or integer)  number  followed  by	a
	       scale  factor.	For  all  limits  other  than cputime the default scale is `k' or
	       `kilobytes' (1024 bytes); a scale factor of `m' or `megabytes' may also	be  used.
	       For  cputime  the  default  scaling is `seconds', while `m' for minutes or `h' for
	       hours, or a time of the form `mm:ss' giving minutes and seconds may be used.

	       For both resource names and scale factors, unambiguous prefixes of the names  suf-

       log (+) Prints the watch shell variable and reports on each user indicated in watch who is
	       logged in, regardless of when they last logged in.  See also watchlog.

       login   Terminates a login shell, replacing it with an instance of /bin/login. This is one
	       way to log off, included for compatibility with sh(1).

       logout  Terminates a login shell.  Especially useful if ignoreeof is set.

       ls-F [-switch ...] [file ...] (+)
	       Lists  files  like  `ls	-F', but much faster.  It identifies each type of special
	       file in the listing with a special character:

	       /   Directory
	       *   Executable
	       #   Block device
	       %   Character device
	       |   Named pipe (systems with named pipes only)
	       =   Socket (systems with sockets only)
	       @   Symbolic link (systems with symbolic links only)
	       +   Hidden directory (AIX only) or context dependent (HP/UX only)
	       :   Network special (HP/UX only)

	       If the listlinks shell variable is set, symbolic  links	are  identified  in  more
	       detail (on only systems that have them, of course):

	       @   Symbolic link to a non-directory
	       >   Symbolic link to a directory
	       &   Symbolic link to nowhere

	       listlinks  also	slows down ls-F and causes partitions holding files pointed to by
	       symbolic links to be mounted.

	       If the listflags shell variable is set to `x', `a'  or  `A',  or  any  combination
	       thereof (e.g., `xA'), they are used as flags to ls-F, making it act like `ls -xF',
	       `ls -Fa', `ls -FA' or a combination (e.g., `ls -FxA').  On machines where `ls  -C'
	       is  not the default, ls-F acts like `ls -CF', unless listflags contains an `x', in
	       which case it acts like `ls -xF'.  ls-F passes its arguments to	ls(1)  if  it  is
	       given any switches, so `alias ls ls-F' generally does the right thing.

	       The  ls-F  builtin can list files using different colors depending on the filetype
	       or extension.  See the color tcsh variable and the LS_COLORS environment variable.

       migrate [-site] pid|%jobid ... (+)
       migrate -site (+)
	       The first form migrates the process or job to the site specified  or  the  default
	       site  determined  by  the  system path.	The second form is equivalent to `migrate
	       -site $$': it migrates the current process to the specified site.   Migrating  the
	       shell  itself  can  cause  unexpected behavior, because the shell does not like to
	       lose its tty.  (TCF only)

       newgrp [-] group (+)
	       Equivalent to `exec newgrp'; see newgrp(1).  Available only if the  shell  was  so
	       compiled; see the version shell variable.

       nice [+number] [command]
	       Sets  the  scheduling  priority for the shell to number, or, without number, to 4.
	       With command, runs command at the appropriate priority.	The greater  the  number,
	       the  less  cpu  the process gets.  The super-user may specify negative priority by
	       using `nice -number ...'.  Command is always executed  in  a  sub-shell,  and  the
	       restrictions placed on commands in simple if statements apply.

       nohup [command]
	       With  command,  runs  command  such that it will ignore hangup signals.	Note that
	       commands may set their own response to  hangups,  overriding  nohup.   Without  an
	       argument  (allowed in only a shell script), causes the shell to ignore hangups for
	       the remainder of the script.  See also Signal handling and the  hup  builtin  com-

       notify [%job ...]
	       Causes  the  shell to notify the user asynchronously when the status of any of the
	       specified jobs (or, without %job, the current job)  changes,  instead  of  waiting
	       until the next prompt as is usual.  job may be a number, a string, `', `%', `+' or
	       `-' as described under Jobs.  See also the notify shell variable.

       onintr [-|label]
	       Controls the action of the shell on interrupts.	Without arguments,  restores  the
	       default	action of the shell on interrupts, which is to terminate shell scripts or
	       to return to the terminal command input level.  With `-', causes all interrupts to
	       be ignored.  With label, causes the shell to execute a `goto label' when an inter-
	       rupt is received or a child process terminates because it was interrupted.

	       onintr is ignored if the shell is running detached and  in  system  startup  files
	       (see FILES), where interrupts are disabled anyway.

       popd [-p] [-l] [-n|-v] [+n]
	       Without	arguments, pops the directory stack and returns to the new top directory.
	       With a number `+n', discards the n'th entry in the stack.

	       Finally, all forms of popd print the final directory stack, just like  dirs.   The
	       pushdsilent shell variable can be set to prevent this and the -p flag can be given
	       to override pushdsilent.  The -l, -n and -v flags have the same effect on popd  as
	       on dirs.  (+)

       printenv [name] (+)
	       Prints  the names and values of all environment variables or, with name, the value
	       of the environment variable name.

       pushd [-p] [-l] [-n|-v] [name|+n]
	       Without arguments, exchanges the top two elements  of  the  directory  stack.   If
	       pushdtohome  is	set,  pushd  without arguments does `pushd ~', like cd.  (+) With
	       name, pushes the current working directory onto the directory stack and changes to
	       name.   If  name  is  `-' it is interpreted as the previous working directory (see
	       Filename substitution).	(+) If dunique is set, pushd  removes  any  instances  of
	       name  from  the	stack  before pushing it onto the stack.  (+) With a number `+n',
	       rotates the nth element of the directory stack around to be the	top  element  and
	       changes	to  it.   If dextract is set, however, `pushd +n' extracts the nth direc-
	       tory, pushes it onto the top of the stack and changes to it.  (+)

	       Finally, all forms of pushd print the final directory stack, just like dirs.   The
	       pushdsilent shell variable can be set to prevent this and the -p flag can be given
	       to override pushdsilent.  The -l, -n and -v flags have the same effect on pushd as
	       on dirs.  (+)

       rehash  Causes  the  internal  hash  table  of the contents of the directories in the path
	       variable to be recomputed.  This is needed if new commands are added  to  directo-
	       ries  in  path  while you are logged in.  This should be necessary only if you add
	       commands to one of your own directories, or if a systems  programmer  changes  the
	       contents  of one of the system directories.  Also flushes the cache of home direc-
	       tories built by tilde expansion.

       repeat count command
	       The specified command, which is subject to the same restrictions as the command in
	       the  one line if statement above, is executed count times.  I/O redirections occur
	       exactly once, even if count is 0.

       rootnode //nodename (+)
	       Changes the rootnode to //nodename, so that `/' will be	interpreted  as  `//node-
	       name'.  (Domain/OS only)

       sched (+)
       sched [+]hh:mm command (+)
       sched -n (+)
	       The  first  form prints the scheduled-event list.  The sched shell variable may be
	       set to define the format in which the scheduled-event list is printed.  The second
	       form adds command to the scheduled-event list.  For example,

		   > sched 11:00 echo It\'s eleven o\'clock.

	       causes  the  shell  to  echo  `It's eleven o'clock.' at 11 AM.  The time may be in
	       12-hour AM/PM format

		   > sched 5pm set prompt='[%h] It\'s after 5; go home: >'

	       or may be relative to the current time:

		   > sched +2:15 /usr/lib/uucp/uucico -r1 -sother

	       A relative time specification may not use AM/PM format.	The  third  form  removes
	       item n from the event list:

		   > sched
			1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
			2  Wed Apr  4 17:00  set prompt=[%h] It's after 5; go home: >
		   > sched -2
		   > sched
			1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother

	       A  command in the scheduled-event list is executed just before the first prompt is
	       printed after the time when the command is scheduled.  It is possible to miss  the
	       exact  time  when the command is to be run, but an overdue command will execute at
	       the next prompt.  A command which comes due while the shell is  waiting	for  user
	       input  is  executed  immediately.  However, normal operation of an already-running
	       command will not be interrupted so that a scheduled-event list element may be run.

	       This mechanism is similar to, but not the same as, the at(1) command on some  Unix
	       systems.   Its  major disadvantage is that it may not run a command at exactly the
	       specified time.	Its major advantage is that because sched runs directly from  the
	       shell,  it  has	access	to shell variables and other structures.  This provides a
	       mechanism for changing one's working environment based on the time of day.

       set name ...
       set name=word ...
       set [-r] [-f|-l] name=(wordlist) ... (+)
       set name[index]=word ...
       set -r (+)
       set -r name ... (+)
       set -r name=word ... (+)
	       The first form of the command prints the value of all shell variables.	Variables
	       which  contain  more  than  a single word print as a parenthesized word list.  The
	       second form sets name to the null string.  The third form sets name to the  single
	       word.   The  fourth form sets name to the list of words in wordlist.  In all cases
	       the value is command and filename expanded.  If -r is specified, the value is  set
	       read-only.   If -f or -l are specified, set only unique words keeping their order.
	       -f prefers the first occurrence of a word, and -l the last.  The fifth  form  sets
	       the  index'th  component  of name to word; this component must already exist.  The
	       sixth form lists only the names of all shell variables that  are  read-only.   The
	       seventh form makes name read-only, whether or not it has a value.  The second form
	       sets name to the null string.  The eighth form is the same as the third form,  but
	       make name read-only at the same time.

	       These arguments can be repeated to set and/or make read-only multiple variables in
	       a single set command.  Note, however, that  variable  expansion	happens  for  all
	       arguments  before  any setting occurs.  Note also that `=' can be adjacent to both
	       name and word or separated from both by whitespace, but cannot be adjacent to only
	       one or the other.  See also the unset builtin command.

       setenv [name [value]]
	       Without	arguments,  prints  the  names	and  values of all environment variables.
	       Given name, sets the environment variable name to value or, without value, to  the
	       null string.

       setpath path (+)
	       Equivalent to setpath(1).  (Mach only)

       setspath LOCAL|site|cpu ... (+)
	       Sets the system execution path.	(TCF only)

       settc cap value (+)
	       Tells  the  shell to believe that the terminal capability cap (as defined in term-
	       cap(5)) has the value value.  No sanity checking is done.  Concept terminal  users
	       may have to `settc xn no' to get proper wrapping at the rightmost column.

       setty [-d|-q|-x] [-a] [[+|-]mode] (+)
	       Controls  which	tty  modes  (see Terminal management) the shell does not allow to
	       change.	-d, -q or -x tells setty to act on the `edit', `quote' or  `execute'  set
	       of tty modes respectively; without -d, -q or -x, `execute' is used.

	       Without	other  arguments, setty lists the modes in the chosen set which are fixed
	       on (`+mode') or off (`-mode').  The available modes, and thus  the  display,  vary
	       from  system to system.	With -a, lists all tty modes in the chosen set whether or
	       not they are fixed.  With +mode, -mode or mode, fixes mode on or  off  or  removes
	       control	from  mode  in	the  chosen set.  For example, `setty +echok echoe' fixes
	       `echok' mode on and allows commands to turn `echoe' mode on or off, both when  the
	       shell is executing commands.

       setxvers [string] (+)
	       Set the experimental version prefix to string, or removes it if string is omitted.
	       (TCF only)

       shift [variable]
	       Without arguments, discards argv[1] and shifts the members of argv  to  the  left.
	       It  is  an  error  for  argv not to be set or to have less than one word as value.
	       With variable, performs the same function on variable.

       source [-h] name [args ...]
	       The shell reads and executes commands from name.  The commands are not  placed  on
	       the  history  list.   If  any args are given, they are placed in argv.  (+) source
	       commands may be nested; if they are nested too deeply the shell	may  run  out  of
	       file  descriptors.  An error in a source at any level terminates all nested source
	       commands.  With -h, commands are placed on the history list instead of being  exe-
	       cuted, much like `history -L'.

       stop %job|pid ...
	       Stops  the specified jobs or processes which are executing in the background.  job
	       may be a number, a string, `', `%', `+' or `-' as described under Jobs.	There  is
	       no default job; saying just `stop' does not stop the current job.

       suspend Causes  the shell to stop in its tracks, much as if it had been sent a stop signal
	       with ^Z.  This is most often used to stop shells started by su(1).

       switch (string)
       case str1:
       endsw   Each case label is successively matched, against the  specified	string	which  is
	       first command and filename expanded.  The file metacharacters `*', `?' and `[...]'
	       may be used in the case labels, which are  variable  expanded.	If  none  of  the
	       labels  match  before  a `default' label is found, then the execution begins after
	       the default label.  Each case label and the  default  label  must  appear  at  the
	       beginning  of  a line.  The command breaksw causes execution to continue after the
	       endsw.  Otherwise control may fall through case labels and default labels as in C.
	       If no label matches and there is no default, execution continues after the endsw.

       telltc (+)
	       Lists the values of all terminal capabilities (see termcap(5)).

       time [command]
	       Executes command (which must be a simple command, not an alias, a pipeline, a com-
	       mand list or a parenthesized command list) and prints a time summary as	described
	       under  the  time  variable.   If necessary, an extra shell is created to print the
	       time statistic when the command completes.  Without command, prints a time summary
	       for the current shell and its children.

       umask [value]
	       Sets  the file creation mask to value, which is given in octal.	Common values for
	       the mask are 002, giving all access to the group and read and  execute  access  to
	       others,	and 022, giving read and execute access to the group and others.  Without
	       value, prints the current file creation mask.

       unalias pattern
	       Removes all aliases whose names match  pattern.	 `unalias  *'  thus  removes  all
	       aliases.  It is not an error for nothing to be unaliased.

       uncomplete pattern (+)
	       Removes	all  completions  whose names match pattern.  `uncomplete *' thus removes
	       all completions.  It is not an error for nothing to be uncompleted.

       unhash  Disables use of the internal hash table to speed location of executed programs.

       universe universe (+)
	       Sets the universe to universe.  (Masscomp/RTU only)

       unlimit [-h] [resource]
	       Removes the limitation on resource or, if no resource is specified,  all  resource
	       limitations.  With -h, the corresponding hard limits are removed.  Only the super-
	       user may do this.

       unset pattern
	       Removes all variables whose  names  match  pattern,  unless  they  are  read-only.
	       `unset  *'  thus  removes  all  variables unless they are read-only; this is a bad
	       idea.  It is not an error for nothing to be unset.

       unsetenv pattern
	       Removes all environment variables whose names match pattern.   `unsetenv  *'  thus
	       removes	all  environment  variables;  this is a bad idea.  It is not an error for
	       nothing to be unsetenved.

       ver [systype [command]] (+)
	       Without arguments, prints SYSTYPE.  With systype, sets SYSTYPE to  systype.   With
	       systype	and  command, executes command under systype.  systype may be `bsd4.3' or
	       `sys5.3'.  (Domain/OS only)

       wait    The shell waits for all background jobs.  If the shell is interactive,  an  inter-
	       rupt  will disrupt the wait and cause the shell to print the names and job numbers
	       of all outstanding jobs.

       warp universe (+)
	       Sets the universe to universe.  (Convex/OS only)

       watchlog (+)
	       An alternate name for the log builtin command (q.v.).  Available only if the shell
	       was so compiled; see the version shell variable.

       where command (+)
	       Reports	all  known instances of command, including aliases, builtins and executa-
	       bles in path.

       which command (+)
	       Displays the command that will be executed by the shell after substitutions,  path
	       searching,  etc.   The  builtin	command  is  just like which(1), but it correctly
	       reports tcsh aliases and builtins and is 10 to 100 times  faster.   See	also  the
	       which-command editor command.

       while (expr)
       end     Executes  the  commands	between  the  while  and  the matching end while expr (an
	       expression, as described under Expressions) evaluates  non-zero.   while  and  end
	       must  appear alone on their input lines.  break and continue may be used to termi-
	       nate or continue the loop prematurely.  If the input is a terminal,  the  user  is
	       prompted the first time through the loop as with foreach.

   Special aliases (+)
       If  set, each of these aliases executes automatically at the indicated time.  They are all
       initially undefined.

       beepcmd Runs when the shell wants to ring the terminal bell.

       cwdcmd  Runs after every change of working directory.  For example, if the user is working
	       on  an  X window system using xterm(1) and a re-parenting window manager that sup-
	       ports title bars such as twm(1) and does

		   > alias cwdcmd  'echo -n "^[]2;${HOST}:$cwd ^G"'

	       then the shell will change the title of the running xterm(1) to be the name of the
	       host,  a  colon, and the full current working directory.  A fancier way to do that

		   > alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'

	       This will put the hostname and working directory on the title  bar  but	only  the
	       hostname in the icon manager menu.

	       Note that putting a cd, pushd or popd in cwdcmd may cause an infinite loop.  It is
	       the author's opinion that anyone doing so will get what they deserve.

       jobcmd  Runs before each command gets executed, or when the command changes  state.   This
	       is similar to postcmd, but it does not print builtins.

		   > alias jobcmd  'echo -n "^[]2\;\!#^G"'

	       then executing vi foo.c will put the command string in the xterm title bar.

	       Invoked by the run-help editor command.	The command name for which help is sought
	       is passed as sole argument.  For example, if one does

		   > alias helpcommand '\!:1 --help'

	       then the help display of the command itself will be invoked, using  the	GNU  help
	       calling convention.  Currently there is no easy way to account for various calling
	       conventions (e.g., the customary Unix `-h'), except by using a table of many  com-

	       Runs every tperiod minutes.  This provides a convenient means for checking on com-
	       mon but infrequent changes such as new mail.  For example, if one does

		   > set tperiod = 30
		   > alias periodic checknews

	       then the checknews(1) program runs every 30 minutes.  If periodic is set but  tpe-
	       riod is unset or set to 0, periodic behaves like precmd.

       precmd  Runs just before each prompt is printed.  For example, if one does

		   > alias precmd date

	       then  date(1)  runs  just before the shell prompts for each command.  There are no
	       limits on what precmd can be set to do, but discretion should be used.

       postcmd Runs before each command gets executed.

		   > alias postcmd  'echo -n "^[]2\;\!#^G"'

	       then executing vi foo.c will put the command string in the xterm title bar.

       shell   Specifies the interpreter for executable scripts which do not  themselves  specify
	       an  interpreter.   The first word should be a full path name to the desired inter-
	       preter (e.g., `/bin/csh' or `/usr/local/bin/tcsh').

   Special shell variables
       The variables described in this section have special meaning to the shell.

       The shell sets addsuffix, argv, autologout, command, echo_style, edit, gid,  group,  home,
       loginsh, oid, path, prompt, prompt2, prompt3, shell, shlvl, tcsh, term, tty, uid, user and
       version at startup; they do not change thereafter unless changed by the user.   The  shell
       updates cwd, dirstack, owd and status when necessary, and sets logout on logout.

       The  shell synchronizes afsuser, group, home, path, shlvl, term and user with the environ-
       ment variables of the same names: whenever the  environment  variable  changes  the  shell
       changes the corresponding shell variable to match (unless the shell variable is read-only)
       and vice versa.	Note that although cwd and PWD have identical meanings, they are not syn-
       chronized  in  this  manner,  and that the shell automatically interconverts the different
       formats of path and PATH.

       addsuffix (+)
	       If set, filename completion adds `/' to the end of directories and a space to  the
	       end of normal files when they are matched exactly.  Set by default.

       afsuser (+)
	       If set, autologout's autolock feature uses its value instead of the local username
	       for kerberos authentication.

       ampm (+)
	       If set, all times are shown in 12-hour AM/PM format.

       argv    The arguments to the shell.  Positional parameters are taken from argv, i.e., `$1'
	       is  replaced by `$argv[1]', etc.  Set by default, but usually empty in interactive

       autocorrect (+)
	       If set, the spell-word editor command is invoked automatically before each comple-
	       tion attempt.

       autoexpand (+)
	       If  set,  the  expand-history  editor command is invoked automatically before each
	       completion attempt.

       autolist (+)
	       If set, possibilities are  listed  after  an  ambiguous	completion.   If  set  to
	       `ambiguous',  possibilities  are  listed  only when no new characters are added by

       autologout (+)
	       The first word is the number of minutes of  inactivity  before  automatic  logout.
	       The  optional  second word is the number of minutes of inactivity before automatic
	       locking.  When the shell automatically logs out, it prints `auto-logout', sets the
	       variable logout to `automatic' and exits.  When the shell automatically locks, the
	       user is required to enter  his  password  to  continue  working.   Five	incorrect
	       attempts  result in automatic logout.  Set to `60' (automatic logout after 60 min-
	       utes, and no locking) by default in login and superuser shells,	but  not  if  the
	       shell  thinks  it  is running under a window system (i.e., the DISPLAY environment
	       variable is set), the tty is a pseudo-tty (pty) or the shell was not  so  compiled
	       (see  the  version  shell  variable).  See also the afsuser and logout shell vari-

       backslash_quote (+)
	       If set, backslashes (`\') always quote `\', `'', and `"'.  This may  make  complex
	       quoting tasks easier, but it can cause syntax errors in csh(1) scripts.

       catalog The  file  name	of  the message catalog.  If set, tcsh use `tcsh.${catalog}' as a
	       message catalog instead of default `tcsh'.

       cdpath  A list of directories in which cd should search for subdirectories if they  aren't
	       found in the current directory.

       color   If  set,  it enables color display for the builtin ls-F and it passes --color=auto
	       to ls.  Alternatively, it can be set to only ls-F or only ls to	enable	color  to
	       only one command.  Setting it to nothing is equivalent to setting it to (ls-F ls).

	       If  set, it enables color escape sequence for NLS message files.  And display col-
	       orful NLS messages.

       command (+)
	       If set, the command which was passed to the shell with the -c flag (q.v.).

       complete (+)
	       If set to `enhance', completion 1) ignores case and 2) considers periods,  hyphens
	       and  underscores  (`.',	`-' and `_') to be word separators and hyphens and under-
	       scores to be equivalent.

       continue (+)
	       If set to a list of commands, the shell will continue the listed commands, instead
	       of starting a new one.

       continue_args (+)
	       Same as continue, but the shell will execute:

		   echo `pwd` $argv > ~/.<cmd>_pause; %<cmd>

       correct (+)
	       If  set	to `cmd', commands are automatically spelling-corrected.  If set to `com-
	       plete', commands are automatically completed.  If set to `all', the entire command
	       line is corrected.

       cwd     The  full  pathname of the current directory.  See also the dirstack and owd shell

       dextract (+)
	       If set, `pushd +n' extracts the nth directory from the directory stack rather than
	       rotating it to the top.

       dirsfile (+)
	       The default location in which `dirs -S' and `dirs -L' look for a history file.  If
	       unset, ~/.cshdirs is used.  Because only  ~/.tcshrc  is	normally  sourced  before
	       ~/.cshdirs, dirsfile should be set in ~/.tcshrc rather than ~/.login.

       dirstack (+)
	       An  array  of  all  the directories on the directory stack.  `$dirstack[1]' is the
	       current working directory, `$dirstack[2]' the first directory on the  stack,  etc.
	       Note  that  the	current working directory is `$dirstack[1]' but `=0' in directory
	       stack substitutions, etc.   One	can  change  the  stack  arbitrarily  by  setting
	       dirstack, but the first element (the current working directory) is always correct.
	       See also the cwd and owd shell variables.

       dspmbyte (+)
	       If set to `euc', it enables display and editing EUC-kanji(Japanese) code.  If  set
	       to  `sjis',  it	enables  display and editing Shift-JIS(Japanese) code.	If set to
	       `big5', it enables display and editing Big5(Chinese) code.  If set to  `utf8',  it
	       enables	display  and editing Utf8(Unicode) code.  If set to the following format,
	       it enables display and editing of original multi-byte code format:

		   > set dspmbyte = 0000....(256 bytes)....0000

	       The table requires just 256 bytes.  Each character of 256  characters  corresponds
	       (from  left  to right) to the ASCII codes 0x00, 0x01, ... 0xff.	Each character is
	       set to number 0,1,2 and 3.  Each number has the following meaning:
		 0 ... not used for multi-byte characters.
		 1 ... used for the first byte of a multi-byte character.
		 2 ... used for the second byte of a multi-byte character.
		 3 ... used for both the first byte and second byte of a multi-byte character.

	       If set to `001322', the first character (means 0x00 of the ASCII code) and  second
	       character  (means  0x01	of  ASCII code) are set to `0'.  Then, it is not used for
	       multi-byte characters.  The 3rd character(0x02) is set to '2', indicating that it
	       is  used for the first byte of a multi-byte character.  The 4th character(0x03) is
	       set '3'.  It is used for both the first byte and the second byte of  a  multi-byte
	       character.  The 5th and 6th characters (0x04,0x05) are set to '2', indicating that
	       they are used for the second byte of a multi-byte character.

	       The GNU fileutils version of ls cannot display multi-byte filenames without the -N
	       (  --literal  )	option.    If  you are using this version, set the second word of
	       dspmbyte to "ls".  If not, for example, "ls-F -l" cannot display multi-byte  file-

	       This  variable  can only be used if KANJI and DSPMBYTE has been defined at compile

       dunique (+)
	       If set, pushd removes any instances of name from the stack before pushing it  onto
	       the stack.

       echo    If set, each command with its arguments is echoed just before it is executed.  For
	       non-builtin commands all expansions occur before echoing.   Builtin  commands  are
	       echoed  before  command and filename substitution, because these substitutions are
	       then done selectively.  Set by the -x command line option.

       echo_style (+)
	       The style of the echo builtin.  May be set to

	       bsd     Don't echo a newline if the first argument is `-n'.
	       sysv    Recognize backslashed escape sequences in echo strings.
	       both    Recognize both  the  `-n'  flag	and  backslashed  escape  sequences;  the
	       none    Recognize neither.

	       Set  by	default  to  the  local system default.  The BSD and System V options are
	       described in the echo(1) man pages on the appropriate systems.

       edit (+)
	       If set, the command-line editor is used.  Set by default in interactive shells.

       ellipsis (+)
	       If set, the `%c'/`%.' and `%C' prompt sequences (see the  prompt  shell	variable)
	       indicate skipped directories with an ellipsis (`...')  instead of `/<skipped>'.

       fignore (+)
	       Lists file name suffixes to be ignored by completion.

       filec   In  tcsh,  completion  is  always used and this variable is ignored by default. If
	       edit is unset, then the traditional csh completion is used.  If set in csh,  file-
	       name completion is used.

       gid (+) The user's real group ID.

       group (+)
	       The user's group name.

	       A  string  value  determining  the characters used in History substitution (q.v.).
	       The first character of its value is used as the	history  substitution  character,
	       replacing  the  default character `!'.  The second character of its value replaces
	       the character `^' in quick substitutions.

       histdup (+)
	       Controls handling of duplicate entries in the history list.  If set to `all'  only
	       unique  history	events are entered in the history list.  If set to `prev' and the
	       last history event is the same as the current command, then the current command is
	       not  entered in the history.  If set to `erase' and the same event is found in the
	       history list, that old event gets erased and the current one gets inserted.   Note
	       that the `prev' and `all' options renumber history events so there are no gaps.

       histfile (+)
	       The  default  location  in  which `history -S' and `history -L' look for a history
	       file.  If unset, ~/.history is used.  histfile is useful  when  sharing	the  same
	       home  directory	between  different machines, or when saving separate histories on
	       different terminals.  Because only ~/.tcshrc is normally  sourced  before  ~/.his-
	       tory, histfile should be set in ~/.tcshrc rather than ~/.login.

       histlit (+)
	       If  set,  builtin  and  editor commands and the savehist mechanism use the literal
	       (unexpanded) form of lines in the history list.	See also the  toggle-literal-his-
	       tory editor command.

       history The  first word indicates the number of history events to save.	The optional sec-
	       ond word (+) indicates the format in which  history  is	printed;  if  not  given,
	       `%h\t%T\t%R\n'  is  used.   The format sequences are described below under prompt;
	       note the variable meaning of `%R'.  Set to `100' by default.

       home    Initialized to the home directory of the invoker.  The filename expansion  of  `~'
	       refers to this variable.

	       If  set to the empty string or `0' and the input device is a terminal, the end-of-
	       file command (usually generated by the user by  typing  `^D'  on  an  empty  line)
	       causes  the  shell  to print `Use "exit" to leave tcsh.' instead of exiting.  This
	       prevents the shell from accidentally being killed.  If set  to  a  number  n,  the
	       shell  ignores n - 1 consecutive end-of-files and exits on the nth.  (+) If unset,
	       `1' is used, i.e., the shell exits on a single `^D'.

       implicitcd (+)
	       If set, the shell treats a directory name typed as a command as though it  were	a
	       request	to  change to that directory.  If set to verbose, the change of directory
	       is echoed to the standard output.  This behavior is inhibited  in  non-interactive
	       shell scripts, or for command strings with more than one word.  Changing directory
	       takes precedence over executing a like-named command, but it is done  after  alias
	       substitutions.  Tilde and variable expansions work as expected.

       inputmode (+)
	       If  set	to  `insert'  or `overwrite', puts the editor into that input mode at the
	       beginning of each line.

       killdup (+)
	       Controls handling of duplicate entries in the kill ring.  If  set  to  `all'  only
	       unique strings are entered in the kill ring.  If set to `prev' and the last killed
	       string is the same as the current killed string, then the current  string  is  not
	       entered	in  the ring.  If set to `erase' and the same string is found in the kill
	       ring, the old string is erased and the current one is inserted.

       killring (+)
	       Indicates the number of killed strings to keep in memory.  Set to `30' by default.
	       If  unset  or  set  to  less  than `2', the shell will only keep the most recently
	       killed string.

       listflags (+)
	       If set to `x', `a' or `A', or any combination thereof (e.g., `xA'), they are  used
	       as flags to ls-F, making it act like `ls -xF', `ls -Fa', `ls -FA' or a combination
	       (e.g., `ls -FxA'): `a' shows all files (even if they start with a `.'), `A'  shows
	       all  files  but `.' and `..', and `x' sorts across instead of down.  If the second
	       word of listflags is set, it is used as the path to `ls(1)'.

       listjobs (+)
	       If set, all jobs are listed when a job is suspended.  If set to `long', the  list-
	       ing is in long format.

       listlinks (+)
	       If  set,  the  ls-F  builtin command shows the type of file to which each symbolic
	       link points.

       listmax (+)
	       The maximum number of items which the list-choices editor command will list  with-
	       out asking first.

       listmaxrows (+)
	       The  maximum  number  of  rows of items which the list-choices editor command will
	       list without asking first.

       loginsh (+)
	       Set by the shell if it is a login shell.  Setting or unsetting it within  a  shell
	       has no effect.  See also shlvl.

       logout (+)
	       Set  by	the shell to `normal' before a normal logout, `automatic' before an auto-
	       matic logout, and `hangup' if the shell was killed by a hangup signal (see  Signal
	       handling).  See also the autologout shell variable.

       mail    The  names  of  the  files or directories to check for incoming mail, separated by
	       whitespace, and optionally preceded by a numeric word.  Before each prompt, if  10
	       minutes have passed since the last check, the shell checks each file and says `You
	       have new mail.' (or, if mail contains  multiple	files,	`You  have  new  mail  in
	       name.')	if  the filesize is greater than zero in size and has a modification time
	       greater than its access time.

	       If you are in a login shell, then no mail file is reported unless it has been mod-
	       ified after the time the shell has started up, to prevent redundant notifications.
	       Most login programs will tell you whether or not you have mail when you log in.

	       If a file specified in mail is a directory, the shell will count each file  within
	       that  directory as a separate message, and will report `You have n mails.' or `You
	       have n mails in name.' as appropriate.  This functionality is  provided	primarily
	       for those systems which store mail in this manner, such as the Andrew Mail System.

	       If  the	first  word  of  mail is numeric it is taken as a different mail checking
	       interval, in seconds.

	       Under very rare circumstances, the shell may report `You have  mail.'  instead  of
	       `You have new mail.'

       matchbeep (+)
	       If  set	to  `never',  completion never beeps.  If set to `nomatch', it beeps only
	       when there is no match.	If set to `ambiguous, it beeps when  there  are  multiple
	       matches.  If set to `notunique', it beeps when there is one exact and other longer
	       matches.  If unset, `ambiguous' is used.

       nobeep (+)
	       If set, beeping is completely disabled.	See also visiblebell.

	       If set, restrictions are placed on output redirection to insure that files are not
	       accidentally  destroyed	and  that  `>>'  redirections refer to existing files, as
	       described in the Input/output section.

       noding  If set, disable the printing of `DING!' in  the	prompt	time  specifiers  at  the
	       change of hour.

       noglob  If  set,  Filename substitution and Directory stack substitution (q.v.) are inhib-
	       ited.  This is most useful in shell scripts which do not deal with  filenames,  or
	       after  a list of filenames has been obtained and further expansions are not desir-

       nokanji (+)
	       If set and the shell supports Kanji (see the version shell variable), it  is  dis-
	       abled so that the meta key can be used.

	       If  set, a Filename substitution or Directory stack substitution (q.v.) which does
	       not match any existing files is left untouched rather than causing an  error.   It
	       is still an error for the substitution to be malformed, e.g., `echo [' still gives
	       an error.

       nostat (+)
	       A list of directories (or glob-patterns which match directories; see Filename sub-
	       stitution)  that  should  not be stat(2)ed during a completion operation.  This is
	       usually used to exclude directories which take too much time to stat(2), for exam-
	       ple /afs.

       notify  If  set,  the  shell  announces job completions asynchronously.	The default is to
	       present job completions just before printing a prompt.

       oid (+) The user's real organization ID.  (Domain/OS only)

       owd (+) The old working directory, equivalent to the `-' used by cd and pushd.	See  also
	       the cwd and dirstack shell variables.

       path    A list of directories in which to look for executable commands.	A null word spec-
	       ifies the current directory.  If there is no path variable  then  only  full  path
	       names will execute.  path is set by the shell at startup from the PATH environment
	       variable or, if PATH does not exist, to a system-dependent default something  like
	       `(/usr/local/bin  /usr/bsd /bin /usr/bin .)'.  The shell may put `.' first or last
	       in path or omit it entirely depending on how it	was  compiled;	see  the  version
	       shell  variable.   A  shell which is given neither the -c nor the -t option hashes
	       the contents of the directories in path after reading ~/.tcshrc and each time path
	       is  reset.   If	one  adds a new command to a directory in path while the shell is
	       active, one may need to do a rehash for the shell to find it.

       printexitvalue (+)
	       If set and an interactive program exits with a non-zero status, the  shell  prints
	       `Exit status'.

       prompt  The string which is printed before reading each command from the terminal.  prompt
	       may include any of the following formatting sequences (+), which are  replaced  by
	       the given information:

	       %/  The current working directory.
	       %~  The	current  working  directory, but with one's home directory represented by
		   `~' and other users' home directories represented by `~user' as  per  Filename
		   substitution.  `~user' substitution happens only if the shell has already used
		   `~user' in a pathname in the current session.
	       %c[[0]n], %.[[0]n]
		   The trailing component of the current working directory, or n trailing  compo-
		   nents if a digit n is given.  If n begins with `0', the number of skipped com-
		   ponents precede the trailing component(s) in the format  `/<skipped>trailing'.
		   If  the  ellipsis shell variable is set, skipped components are represented by
		   an ellipsis so the whole becomes `...trailing'.  `~' substitution is  done  as
		   in  `%~' above, but the `~' component is ignored when counting trailing compo-
	       %C  Like %c, but without `~' substitution.
	       %h, %!, !
		   The current history event number.
	       %M  The full hostname.
	       %m  The hostname up to the first `.'.
	       %S (%s)
		   Start (stop) standout mode.
	       %B (%b)
		   Start (stop) boldfacing mode.
	       %U (%u)
		   Start (stop) underline mode.
	       %t, %@
		   The time of day in 12-hour AM/PM format.
	       %T  Like `%t', but in 24-hour format (but see the ampm shell variable).
	       %p  The `precise' time of day in 12-hour AM/PM format, with seconds.
	       %P  Like `%p', but in 24-hour format (but see the ampm shell variable).
	       \c  c is parsed as in bindkey.
	       ^c  c is parsed as in bindkey.
	       %%  A single `%'.
	       %n  The user name.
	       %j  The number of jobs.
	       %d  The weekday in `Day' format.
	       %D  The day in `dd' format.
	       %w  The month in `Mon' format.
	       %W  The month in `mm' format.
	       %y  The year in `yy' format.
	       %Y  The year in `yyyy' format.
	       %l  The shell's tty.
	       %L  Clears from the end of the prompt to end of the display  or	the  end  of  the
	       %$  Expands the shell or environment variable name immediately after the `$'.
	       %#  `>'	(or  the  first  character  of the promptchars shell variable) for normal
		   users, `#' (or the second character of promptchars) for the superuser.
		   Includes string as a literal escape sequence.   It  should  be  used  only  to
		   change terminal attributes and should not move the cursor location.	This can-
		   not be the last sequence in prompt.
	       %?  The return code of the command executed just before the prompt.
	       %R  In prompt2, the status of the parser.  In prompt3, the corrected  string.   In
		   history, the history string.

	       `%B',  `%S',  `%U'  and `%{string%}' are available in only eight-bit-clean shells;
	       see the version shell variable.

	       The bold, standout and underline sequences are often used to distinguish  a  supe-
	       ruser shell.  For example,

		   > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
		   tut [37] [2:54pm] [/usr/accts/sys] you rang? _

	       If  `%t',  `%@',  `%T',	`%p',  or `%P' is used, and noding is not set, then print
	       `DING!' on the change of hour (i.e, `:00' minutes) instead of the actual time.

	       Set by default to `%# ' in interactive shells.

       prompt2 (+)
	       The string with which to prompt in while and foreach loops and after lines  ending
	       in `\'.	The same format sequences may be used as in prompt (q.v.); note the vari-
	       able meaning of `%R'.  Set by default to `%R? ' in interactive shells.

       prompt3 (+)
	       The string with which to prompt when  confirming  automatic  spelling  correction.
	       The same format sequences may be used as in prompt (q.v.); note the variable mean-
	       ing of `%R'.  Set by default to `CORRECT>%R (y|n|e|a)? ' in interactive shells.

       promptchars (+)
	       If set (to a two-character string), the `%#' formatting	sequence  in  the  prompt
	       shell  variable is replaced with the first character for normal users and the sec-
	       ond character for the superuser.

       pushdtohome (+)
	       If set, pushd without arguments does `pushd ~', like cd.

       pushdsilent (+)
	       If set, pushd and popd do not print the directory stack.

       recexact (+)
	       If set, completion completes on an exact match even if a longer match is possible.

       recognize_only_executables (+)
	       If set, command listing displays only files  in	the  path  that  are  executable.

       rmstar (+)
	       If set, the user is prompted before `rm *' is executed.

       rprompt (+)
	       The string to print on the right-hand side of the screen (after the command input)
	       when the prompt is being displayed on the left.	It recognizes the same formatting
	       characters  as prompt.  It will automatically disappear and reappear as necessary,
	       to ensure that command input isn't obscured, and will appear only if  the  prompt,
	       command input, and itself will fit together on the first line.  If edit isn't set,
	       then rprompt will be printed after the prompt and before the command input.

       savedirs (+)
	       If set, the shell does `dirs -S' before exiting.  If the first word is  set  to	a
	       number, at most that many directory stack entries are saved.

	       If set, the shell does `history -S' before exiting.  If the first word is set to a
	       number, at most that many lines are saved.  (The number must be less than or equal
	       to  history.)   If  the	second word is set to `merge', the history list is merged
	       with the existing history file instead of replacing  it	(if  there  is	one)  and
	       sorted by time stamp and the most recent events are retained.  (+)

       sched (+)
	       The  format  in	which  the  sched builtin command prints scheduled events; if not
	       given, `%h\t%T\t%R\n' is used.  The format sequences  are  described  above  under
	       prompt; note the variable meaning of `%R'.

       shell   The  file in which the shell resides.  This is used in forking shells to interpret
	       files which have execute bits set, but which are not  executable  by  the  system.
	       (See  the  description of Builtin and non-builtin command execution.)  Initialized
	       to the (system-dependent) home of the shell.

       shlvl (+)
	       The number of nested shells.  Reset to 1 in login shells.  See also loginsh.

       status  The status returned by the last command.  If it terminated abnormally,  then  0200
	       is  added  to the status.  Builtin commands which fail return exit status `1', all
	       other builtin commands return status `0'.

       symlinks (+)
	       Can be set to several different values to control symbolic link (`symlink')  reso-

	       If  set to `chase', whenever the current directory changes to a directory contain-
	       ing a symbolic link, it is expanded to the real name of the directory to which the
	       link points.  This does not work for the user's home directory; this is a bug.

	       If  set	to `ignore', the shell tries to construct a current directory relative to
	       the current directory before the link was crossed.  This means that cding  through
	       a  symbolic  link and then `cd ..'ing returns one to the original directory.  This
	       affects only builtin commands and filename completion.

	       If set to `expand', the shell tries to fix symbolic links  by  actually	expanding
	       arguments  which  look  like  path  names.   This  affects  any	command, not just
	       builtins.  Unfortunately, this does not work for hard-to-recognize filenames, such
	       as  those  embedded  in	command  options.  Expansion may be prevented by quoting.
	       While this setting is usually the most convenient, it is sometimes misleading  and
	       sometimes  confusing  when  it  fails  to  recognize  an  argument which should be
	       expanded.  A compromise is to use `ignore' and use the editor  command  normalize-
	       path (bound by default to ^X-n) when necessary.

	       Some examples are in order.  First, let's set up some play directories:

		   > cd /tmp
		   > mkdir from from/src to
		   > ln -s from/src to/dst

	       Here's the behavior with symlinks unset,

		   > cd /tmp/to/dst; echo $cwd
		   > cd ..; echo $cwd

	       here's the behavior with symlinks set to `chase',

		   > cd /tmp/to/dst; echo $cwd
		   > cd ..; echo $cwd

	       here's the behavior with symlinks set to `ignore',

		   > cd /tmp/to/dst; echo $cwd
		   > cd ..; echo $cwd

	       and here's the behavior with symlinks set to `expand'.

		   > cd /tmp/to/dst; echo $cwd
		   > cd ..; echo $cwd
		   > cd /tmp/to/dst; echo $cwd
		   > cd ".."; echo $cwd
		   > /bin/echo ..
		   > /bin/echo ".."

	       Note  that `expand' expansion 1) works just like `ignore' for builtins like cd, 2)
	       is prevented by quoting, and 3) happens before filenames are passed to non-builtin

       tcsh (+)
	       The  version  number  of the shell in the format `R.VV.PP', where `R' is the major
	       release number, `VV' the current version and `PP' the patchlevel.

       term    The terminal type.  Usually set in ~/.login as described under Startup  and  shut-

       time    If set to a number, then the time builtin (q.v.) executes automatically after each
	       command which takes more than that many CPU seconds.  If there is a  second  word,
	       it is used as a format string for the output of the time builtin.  (u) The follow-
	       ing sequences may be used in the format string:

	       %U  The time the process spent in user mode in cpu seconds.
	       %S  The time the process spent in kernel mode in cpu seconds.
	       %E  The elapsed (wall clock) time in seconds.
	       %P  The CPU percentage computed as (%U + %S) / %E.
	       %W  Number of times the process was swapped.
	       %X  The average amount in (shared) text space used in Kbytes.
	       %D  The average amount in (unshared) data/stack space used in Kbytes.
	       %K  The total space used (%X + %D) in Kbytes.
	       %M  The maximum memory the process had in use at any time in Kbytes.
	       %F  The number of major page faults (page needed to be brought from disk).
	       %R  The number of minor page faults.
	       %I  The number of input operations.
	       %O  The number of output operations.
	       %r  The number of socket messages received.
	       %s  The number of socket messages sent.
	       %k  The number of signals received.
	       %w  The number of voluntary context switches (waits).
	       %c  The number of involuntary context switches.

	       Only the first four sequences are supported on systems without BSD resource  limit
	       functions.  The default time format is `%Uu %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww' for
	       systems that support resource usage reporting and `%Uu %Ss %E %P' for systems that
	       do not.

	       Under  Sequent's  DYNIX/ptx, %X, %D, %K, %r and %s are not available, but the fol-
	       lowing additional sequences are:

	       %Y  The number of system calls performed.
	       %Z  The number of pages which are zero-filled on demand.
	       %i  The number of times a process's resident set size was increased by the kernel.
	       %d  The number of times a process's resident set size was decreased by the kernel.
	       %l  The number of read system calls performed.
	       %m  The number of write system calls performed.
	       %p  The number of reads from raw disk devices.
	       %q  The number of writes to raw disk devices.

	       and the default time format is `%Uu %Ss $E %P %I+%Oio %Fpf+%Ww'.   Note	that  the
	       CPU percentage can be higher than 100% on multi-processors.

       tperiod (+)
	       The period, in minutes, between executions of the periodic special alias.

       tty (+) The name of the tty, or empty if not attached to one.

       uid (+) The user's real user ID.

       user    The user's login name.

       verbose If set, causes the words of each command to be printed, after history substitution
	       (if any).  Set by the -v command line option.

       version (+)
	       The version ID stamp.  It contains the shell's version number (see tcsh),  origin,
	       release	date,  vendor,	operating  system  and	machine  (see  VENDOR, OSTYPE and
	       MACHTYPE) and a comma-separated list of options which were set  at  compile  time.
	       Options which are set by default in the distribution are noted.

	       8b  The shell is eight bit clean; default
	       7b  The shell is not eight bit clean
	       nls The system's NLS is used; default for systems with NLS
	       lf  Login shells execute /etc/csh.login before instead of after /etc/csh.cshrc and
		   ~/.login before instead of after ~/.tcshrc and ~/.history.
	       dl  `.' is put last in path for security; default
	       nd  `.' is omitted from path for security
	       vi  vi-style editing is the default rather than emacs
	       dtr Login shells drop DTR when exiting
	       bye bye is a synonym for logout and log is an alternate name for watchlog
	       al  autologout is enabled; default
	       kan Kanji is used if appropriate according to locale settings, unless the  nokanji
		   shell variable is set
	       sm  The system's malloc(3) is used
	       hb  The `#!<program> <args>' convention is emulated when executing shell scripts
	       ng  The newgrp builtin is available
	       rh  The shell attempts to set the REMOTEHOST environment variable
	       afs The shell verifies your password with the kerberos server if local authentica-
		   tion fails.	The afsuser shell variable or the  AFSUSER  environment  variable
		   override your local username if set.

	       An administrator may enter additional strings to indicate differences in the local

       visiblebell (+)
	       If set, a screen flash is used rather than the audible bell.  See also nobeep.

       watch (+)
	       A list of user/terminal pairs to watch for logins and logouts.  If either the user
	       is  `any'  all  terminals  are watched for the given user and vice versa.  Setting
	       watch to `(any any)' watches all users and terminals.  For example,

		   set watch = (george ttyd1 any console $user any)

	       reports activity of the user `george' on ttyd1, any user on the console, and  one-
	       self (or a trespasser) on any terminal.

	       Logins  and logouts are checked every 10 minutes by default, but the first word of
	       watch can be set to a number to check every so many minutes.  For example,

		   set watch = (1 any any)

	       reports any login/logout once every minute.  For the impatient,	the  log  builtin
	       command	triggers a watch report at any time.  All current logins are reported (as
	       with the log builtin) when watch is first set.

	       The who shell variable controls the format of watch reports.

       who (+) The format string for watch messages.  The following sequences are replaced by the
	       given information:

	       %n  The name of the user who logged in/out.
	       %a  The observed action, i.e., `logged on', `logged off' or `replaced olduser on'.
	       %l  The terminal (tty) on which the user logged in/out.
	       %M  The	full hostname of the remote host, or `local' if the login/logout was from
		   the local host.
	       %m  The hostname of the remote host up to the first `.'.  The full name is printed
		   if it is an IP address or an X Window System display.

	       %M  and	%m  are  available  on	only  systems  that  store the remote hostname in
	       /etc/utmp.  If unset, `%n has %a %l from %m.' is used, or `%n has %a %l.' on  sys-
	       tems which don't store the remote hostname.

       wordchars (+)
	       A  list of non-alphanumeric characters to be considered part of a word by the for-
	       ward-word, backward-word etc., editor commands.	If unset, `*?_-.[]~=' is used.

       AFSUSER (+)
	       Equivalent to the afsuser shell variable.

       COLUMNS The number of columns in the terminal.  See Terminal management.

       DISPLAY Used by X Window System (see X(1)).  If set, the shell  does  not  set  autologout

       EDITOR  The  pathname  to  a default editor.  See also the VISUAL environment variable and
	       the run-fg-editor editor command.

       GROUP (+)
	       Equivalent to the group shell variable.

       HOME    Equivalent to the home shell variable.

       HOST (+)
	       Initialized to the name of the machine on which the shell is  running,  as  deter-
	       mined by the gethostname(2) system call.

       HOSTTYPE (+)
	       Initialized to the type of machine on which the shell is running, as determined at
	       compile time.  This variable is obsolete and will be removed in a future version.

       HPATH (+)
	       A colon-separated list of directories in which the run-help editor  command  looks
	       for command documentation.

       LANG    Gives the preferred character environment.  See Native Language System support.

	       If set, only ctype character handling is changed.  See Native Language System sup-

       LINES   The number of lines in the terminal.  See Terminal management.

	       The format of this variable is reminiscent of the termcap(5) file format; a colon-
	       separated list of expressions of the form "xx=string", where "xx" is a two-charac-
	       ter variable name.  The variables with their associated defaults are:

		   no	0      Normal (non-filename) text
		   fi	0      Regular file
		   di	01;34  Directory
		   ln	01;36  Symbolic link
		   pi	33     Named pipe (FIFO)
		   so	01;35  Socket
		   do	01;35  Door
		   bd	01;33  Block device
		   cd	01;32  Character device
		   ex	01;32  Executable file
		   mi	(none) Missing file (defaults to fi)
		   or	(none) Orphaned symbolic link (defaults to ln)
		   lc	^[[    Left code
		   rc	m      Right code
		   ec	(none) End code (replaces lc+no+rc)

	       You need to include only the variables you want to change from the default.

	       File names can also be colorized based on filename extension.  This  is	specified
	       in  the LS_COLORS variable using the syntax "*ext=string".  For example, using ISO
	       6429 codes, to color all C-language source files blue you would specify	"*.c=34".
	       This would color all files ending in .c in blue(34) color.

	       Control	characters  can  be  written  either  in  C-style-escaped notation, or in
	       stty-like ^-notation.  The C-style notation adds ^[ for Escape,	_  for	a  normal
	       space  character,  and  ? for Delete.  In addition, the ^[ escape character can be
	       used to override the default interpretation of ^[, ^, : and =.

	       Each file will be written as <lc> <color-code> <rc> <filename> <ec>.  If the  <ec>
	       code is undefined, the sequence <lc> <no> <rc> will be used instead.  This is gen-
	       erally more convenient to use, but less general.  The left, right  and  end  codes
	       are  provided  so  you  don't have to type common parts over and over again and to
	       support weird terminals; you will generally not need to change them at all  unless
	       your terminal does not use ISO 6429 color sequences but a different system.

	       If  your  terminal  does  use ISO 6429 color codes, you can compose the type codes
	       (i.e., all except the lc, rc, and ec codes) from numerical commands  separated  by
	       semicolons.  The most common commands are:

		       0   to restore default color
		       1   for brighter colors
		       4   for underlined text
		       5   for flashing text
		       30  for black foreground
		       31  for red foreground
		       32  for green foreground
		       33  for yellow (or brown) foreground
		       34  for blue foreground
		       35  for purple foreground
		       36  for cyan foreground
		       37  for white (or gray) foreground
		       40  for black background
		       41  for red background
		       42  for green background
		       43  for yellow (or brown) background
		       44  for blue background
		       45  for purple background
		       46  for cyan background
		       47  for white (or gray) background

	       Not all commands will work on all systems or display devices.

	       A  few  terminal  programs do not recognize the default end code properly.  If all
	       text gets colorized after you do a directory listing, try changing the no  and  fi
	       codes from 0 to the numerical codes for your standard fore- and background colors.

       MACHTYPE (+)
	       The machine type (microprocessor class or machine model), as determined at compile

       NOREBIND (+)
	       If set, printable characters are not rebound to self-insert-command.   See  Native
	       Language System support.

       OSTYPE (+)
	       The operating system, as determined at compile time.

       PATH    A  colon-separated  list of directories in which to look for executables.  Equiva-
	       lent to the path shell variable, but in a different format.

       PWD (+) Equivalent to the cwd shell variable, but not synchronized  to  it;  updated  only
	       after an actual directory change.

       REMOTEHOST (+)
	       The  host  from which the user has logged in remotely, if this is the case and the
	       shell is able to determine it.  Set only if the shell was  so  compiled;  see  the
	       version shell variable.

       SHLVL (+)
	       Equivalent to the shlvl shell variable.

       SYSTYPE (+)
	       The current system type.  (Domain/OS only)

       TERM    Equivalent to the term shell variable.

       TERMCAP The terminal capability string.	See Terminal management.

       USER    Equivalent to the user shell variable.

       VENDOR (+)
	       The vendor, as determined at compile time.

       VISUAL  The  pathname  to  a  default full-screen editor.  See also the EDITOR environment
	       variable and the run-fg-editor editor command.

       /etc/csh.cshrc  Read first by every shell.  ConvexOS, Stellix and Intel use /etc/cshrc and
		       NeXTs use /etc/cshrc.std.  A/UX, AMIX, Cray and IRIX have no equivalent in
		       csh(1), but read this file in tcsh anyway.  Solaris 2.x does not  have  it
		       either, but tcsh reads /etc/.cshrc.  (+)
       /etc/csh.login  Read  by  login	shells after /etc/csh.cshrc.  ConvexOS, Stellix and Intel
		       use /etc/login, NeXTs use /etc/login.std, Solaris 2.x uses /etc/.login and
		       A/UX, AMIX, Cray and IRIX use /etc/cshrc.
       ~/.tcshrc (+)   Read by every shell after /etc/csh.cshrc or its equivalent.
       ~/.cshrc        Read  by  every shell, if ~/.tcshrc doesn't exist, after /etc/csh.cshrc or
		       its equivalent.	This manual uses `~/.tcshrc' to mean  `~/.tcshrc  or,  if
		       ~/.tcshrc is not found, ~/.cshrc'.
       ~/.history      Read  by  login	shells	after  ~/.tcshrc if savehist is set, but see also
       ~/.login        Read by login shells after ~/.tcshrc or ~/.history.  The shell may be com-
		       piled  to  read ~/.login before instead of after ~/.tcshrc and ~/.history;
		       see the version shell variable.
       ~/.cshdirs (+)  Read by login shells after ~/.login if savedirs is set, but see also dirs-
       /etc/csh.logout Read  by  login	shells	at  logout.   ConvexOS,  Stellix  and  Intel  use
		       /etc/logout and NeXTs use /etc/logout.std.  A/UX, AMIX, Cray and IRIX have
		       no  equivalent  in csh(1), but read this file in tcsh anyway.  Solaris 2.x
		       does not have it either, but tcsh reads /etc/.logout.  (+)
       ~/.logout       Read by login shells at logout after /etc/csh.logout or its equivalent.
       /bin/sh	       Used to interpret shell scripts not starting with a `#'.
       /tmp/sh*        Temporary file for `<<'.
       /etc/passwd     Source of home directories for `~name' substitutions.

       The order in which startup files are read may differ if the shell  was  so  compiled;  see
       Startup and shutdown and the version shell variable.

       This  manual  describes tcsh as a single entity, but experienced csh(1) users will want to
       pay special attention to tcsh's new features.

       A command-line editor, which supports GNU Emacs or vi(1)-style key bindings.  See The com-
       mand-line editor and Editor commands.

       Programmable, interactive word completion and listing.  See Completion and listing and the
       complete and uncomplete builtin commands.

       Spelling correction (q.v.) of filenames, commands and variables.

       Editor commands (q.v.) which perform other useful functions in the middle  of  typed  com-
       mands,  including documentation lookup (run-help), quick editor restarting (run-fg-editor)
       and command resolution (which-command).

       An enhanced history mechanism.  Events in the history list are time-stamped.  See also the
       history	command and its associated shell variables, the previously undocumented `#' event
       specifier and new modifiers under History substitution, the  *-history,	history-search-*,
       i-search-*,  vi-search-*  and toggle-literal-history editor commands and the histlit shell

       Enhanced directory parsing and directory stack handling.  See the cd, pushd, popd and dirs
       commands  and their associated shell variables, the description of Directory stack substi-
       tution, the dirstack, owd and symlinks shell variables and the normalize-command and  nor-
       malize-path editor commands.

       Negation in glob-patterns.  See Filename substitution.

       New File inquiry operators (q.v.) and a filetest builtin which uses them.

       A  variety of Automatic, periodic and timed events (q.v.) including scheduled events, spe-
       cial aliases, automatic logout and terminal  locking,  command  timing  and  watching  for
       logins and logouts.

       Support	for  the  Native Language System (see Native Language System support), OS variant
       features (see OS variant support and the echo_style shell variable)  and  system-dependent
       file locations (see FILES).

       Extensive terminal-management capabilities.  See Terminal management.

       New  builtin  commands  including  builtins,  hup, ls-F, newgrp, printenv, which and where

       New variables that make useful information easily available to the shell.   See	the  gid,
       loginsh,  oid, shlvl, tcsh, tty, uid and version shell variables and the HOST, REMOTEHOST,
       VENDOR, OSTYPE and MACHTYPE environment variables.

       A new syntax for including useful information in the prompt string (see prompt).  and spe-
       cial prompts for loops and spelling correction (see prompt2 and prompt3).

       Read-only variables.  See Variable substitution.

       When  a	suspended  command  is restarted, the shell prints the directory it started in if
       this is different from the current directory.  This can be misleading (i.e., wrong) as the
       job may have changed directories internally.

       Shell builtin functions are not stoppable/restartable.  Command sequences of the form `a ;
       b ; c' are also not handled gracefully when stopping is attempted.  If  you  suspend  `b',
       the shell will then immediately execute `c'.  This is especially noticeable if this expan-
       sion results from an alias.  It suffices to place the sequence  of  commands  in  ()'s  to
       force it to a subshell, i.e., `( a ; b ; c )'.

       Control	over  tty  output  after  processes  are  started is primitive; perhaps this will
       inspire someone to work on a good virtual  terminal  interface.	 In  a	virtual  terminal
       interface much more interesting things could be done with output control.

       Alias  substitution is most often used to clumsily simulate shell procedures; shell proce-
       dures should be provided rather than aliases.

       Commands within loops are not placed in the history list.  Control  structures  should  be
       parsed  rather  than being recognized as built-in commands.  This would allow control com-
       mands to be placed anywhere, to be combined with `|', and to be	used  with  `&'  and  `;'

       foreach doesn't ignore here documents when looking for its end.

       It should be possible to use the `:' modifiers on the output of command substitutions.

       The screen update for lines longer than the screen width is very poor if the terminal can-
       not move the cursor up (i.e., terminal type `dumb').

       HPATH and NOREBIND don't need to be environment variables.

       Glob-patterns which do not use `?', `*' or `[]' or which use `{}' or `~' are  not  negated

       The  single-command form of if does output redirection even if the expression is false and
       the command is not executed.

       ls-F includes file identification characters when sorting filenames and	does  not  handle
       control characters in filenames well.  It cannot be interrupted.

       Report  bugs  to tcsh-bugs@mx.gw.com, preferably with fixes.  If you want to help maintain
       and test tcsh, send mail to listserv@mx.gw.com with the text `subscribe tcsh <your  name>'
       on  a  line  by itself in the body.  You can also `subscribe tcsh-bugs <your name>' to get
       all bug reports, or `subscribe tcsh-diffs <your name>' to get the  development  list  plus
       diffs for each patchlevel.

       In  1964,  DEC  produced the PDP-6.  The PDP-10 was a later re-implementation.  It was re-
       christened the DECsystem-10 in 1970 or so when DEC brought out the second model, the KI10.

       TENEX was created at Bolt, Beranek & Newman (a Cambridge,  Massachusetts  think	tank)  in
       1972  as an experiment in demand-paged virtual memory operating systems.  They built a new
       pager for the DEC PDP-10 and created the OS to go with it.  It was extremely successful in

       In 1975, DEC brought out a new model of the PDP-10, the KL10; they intended to have only a
       version of TENEX, which they had licensed from BBN, for the new box.   They  called  their
       version TOPS-20 (their capitalization is trademarked).  A lot of TOPS-10 users (`The OPer-
       ating System for PDP-10') objected; thus DEC found themselves supporting two  incompatible
       systems on the same hardware--but then there were 6 on the PDP-11!

       TENEX,  and  TOPS-20 to version 3, had command completion via a user-code-level subroutine
       library called ULTCMD.  With version 3, DEC moved all that capability and  more	into  the
       monitor	(`kernel'  for	you  Unix  types),  accessed by the COMND% JSYS (`Jump to SYStem'
       instruction, the supervisor call mechanism [are my IBM roots also showing?]).

       The creator of tcsh was impressed by this feature and several others of TENEX and TOPS-20,
       and created a version of csh which mimicked them.

       Words can be no longer than 1024 characters.

       The system limits argument lists to 10240 characters.

       The number of arguments to a command which involves filename expansion is limited to 1/6th
       the number of characters allowed in an argument list.

       Command substitutions may substitute no more characters than are allowed  in  an  argument

       To  detect looping, the shell restricts the number of alias substitutions on a single line
       to 20.

       csh(1), emacs(1), ls(1), newgrp(1), sh(1), setpath(1),  stty(1),  su(1),  tset(1),  vi(1),
       x(1), access(2), execve(2), fork(2), killpg(2), pipe(2), setrlimit(2), sigvec(2), stat(2),
       umask(2), vfork(2), wait(2), malloc(3), setlocale(3), tty(4), a.out(5), termcap(5),  envi-
       ron(7), termio(7), Introduction to the C Shell

       This manual documents tcsh 6.12.00 (Astron) 2002-07-23.

       William Joy
	 Original author of csh(1)
       J.E. Kulp, IIASA, Laxenburg, Austria
	 Job control and directory stack features
       Ken Greer, HP Labs, 1981
	 File name completion
       Mike Ellis, Fairchild, 1983
	 Command name recognition/completion
       Paul Placeway, Ohio State CIS Dept., 1983-1993
	 Command line editor, prompt routines, new glob syntax and numerous fixes and speedups
       Karl Kleinpaste, CCI 1983-4
	 Special aliases, directory stack extraction stuff, login/logout watch, scheduled events,
	 and the idea of the new prompt format
       Rayan Zachariassen, University of Toronto, 1984
	 ls-F and which builtins and numerous bug fixes, modifications and speedups
       Chris Kingsley, Caltech
	 Fast storage allocator routines
       Chris Grevstad, TRW, 1987
	 Incorporated 4.3BSD csh into tcsh
       Christos S. Zoulas, Cornell U. EE Dept., 1987-94
	 Ports to HPUX, SVR2 and SVR3, a SysV version of getwd.c, SHORT_STRINGS support and a new
	 version of sh.glob.c
       James J Dempsey, BBN, and Paul Placeway, OSU, 1988
	 A/UX port
       Daniel Long, NNSC, 1988
       Patrick Wolfe, Kuck and Associates, Inc., 1988
	 vi mode cleanup
       David C Lawrence, Rensselaer Polytechnic Institute, 1989
	 autolist and ambiguous completion listing
       Alec Wolman, DEC, 1989
	 Newlines in the prompt
       Matt Landau, BBN, 1989
       Ray Moody, Purdue Physics, 1989
	 Magic space bar history expansion
       Mordechai ????, Intel, 1989
	 printprompt() fixes and additions
       Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989
	 Automatic spelling correction and prompt3
       Per Hedeland, Ellemtel, Sweden, 1990-
	 Various bugfixes, improvements and manual updates
       Hans J. Albertsson (Sun Sweden)
	 ampm, settc and telltc
       Michael Bloom
	 Interrupt handling fixes
       Michael Fine, Digital Equipment Corp
	 Extended key support
       Eric Schnoebelen, Convex, 1990
	 Convex support, lots of csh bug fixes, save and restore of directory stack
       Ron Flax, Apple, 1990
	 A/UX 2.0 (re)port
       Dan Oscarsson, LTH Sweden, 1990
	 NLS support and simulated NLS support for non NLS sites, fixes
       Johan Widen, SICS Sweden, 1990
	 shlvl, Mach support, correct-line, 8-bit printing
       Matt Day, Sanyo Icon, 1990
	 POSIX termio support, SysV limit fixes
       Jaap Vermeulen, Sequent, 1990-91
	 Vi mode fixes, expand-line, window change fixes, Symmetry port
       Martin Boyer, Institut de recherche d'Hydro-Quebec, 1991
	 autolist  beeping  options,  modified	the history search to search for the whole string
	 from the beginning of the line to the cursor.
       Scott Krotz, Motorola, 1991
	 Minix port
       David Dawes, Sydney U. Australia, Physics Dept., 1991
	 SVR4 job control fixes
       Jose Sousa, Interactive Systems Corp., 1991
	 Extended vi fixes and vi delete command
       Marc Horowitz, MIT, 1991
	 ANSIfication fixes, new exec hashing code, imake fixes, where
       Bruce Sterling Woodcock, sterling@netcom.com, 1991-1995
	 ETA and Pyramid port, Makefile and lint fixes, ignoreeof=n addition, and  various  other
	 portability changes and bug fixes
       Jeff Fink, 1992
	 complete-word-fwd and complete-word-back
       Harry C. Pulley, 1992
	 Coherent port
       Andy Phillips, Mullard Space Science Lab U.K., 1992
	 VMS-POSIX port
       Beto Appleton, IBM Corp., 1992
	 Walking process group fixes, csh bug fixes, POSIX file tests, POSIX SIGHUP
       Scott Bolte, Cray Computer Corp., 1992
	 CSOS port
       Kaveh R. Ghazi, Rutgers University, 1992
	 Tek, m88k, Titan and Masscomp ports and fixes.  Added autoconf support.
       Mark Linderman, Cornell University, 1992
	 OS/2 port
       Mika Liljeberg, liljeber@kruuna.Helsinki.FI, 1992
	 Linux port
       Tim P. Starrin, NASA Langley Research Center Operations, 1993
	 Read-only variables
       Dave Schweisguth, Yale University, 1993-4
	 New man page and tcsh.man2html
       Larry Schwimmer, Stanford University, 1993
	 AFS and HESIOD patches
       Luke Mewburn, RMIT University, 1994-6
	 Enhanced directory printing in prompt, added ellipsis and rprompt.
       Edward Hutchins, Silicon Graphics Inc., 1996
	 Added implicit cd.
       Martin Kraemer, 1997
	 Ported to Siemens Nixdorf EBCDIC machine
       Amol Deshpande, Microsoft, 1997
	 Ported  to  WIN32 (Windows/95 and Windows/NT); wrote all the missing library and message
	 catalog code to interface to Windows.
       Taga Nayuta, 1998
	 Color ls additions.

       Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve  Romig,  Diana	Smetters,
       Bob  Sutterfield, Mark Verber, Elizabeth Zwicky and all the other people at Ohio State for
       suggestions and encouragement

       All the people on the net, for putting up with, reporting  bugs	in,  and  suggesting  new
       additions to each and every version

       Richard M. Alderson III, for writing the `T in tcsh' section

Astron 6.12.00				   23 July 2002 				  TCSH(1)

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