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KSH(1)											   KSH(1)

NAME
       ksh, rksh, pfksh - KornShell, a standard/restricted command and programming language

SYNOPSIS
       ksh [ +-abcefhiknoprstuvxBCDP ] [ -R file ] [ +-o option ] ... [ - ] [ arg ... ]

DESCRIPTION
       Ksh is a command and programming language that executes commands read from a terminal or a
       file.  Rksh is a restricted version of the command interpreter ksh; it is used to  set  up
       login  names  and execution environments whose capabilities are more controlled than those
       of the standard shell.  Rpfksh is a profile shell version of the command interpreter  ksh;
       it  is  used  to  to execute commands with the attributes specified by the user's profiles
       (see pfexec(1)).  See Invocation below for the meaning of arguments to the shell.

   Definitions.
       A metacharacter is one of the following characters:

	      ;   &   (   )   |   <   >   new-line   space   tab

       A blank is a tab or a space.  An identifier is a sequence of letters,  digits,  or  under-
       scores  starting with a letter or underscore.  Identifiers are used as components of vari-
       able names.  A vname is a sequence of one or more identifiers separated by a . and option-
       ally  preceded  by  a  ..   Vnames  are	used as function and variable names.  A word is a
       sequence of characters from the character set defined by  the  current  locale,	excluding
       non-quoted metacharacters.

       A  command  is  a  sequence  of characters in the syntax of the shell language.	The shell
       reads each command and carries out the desired action either directly or by invoking sepa-
       rate  utilities.   A built-in command is a command that is carried out by the shell itself
       without creating a separate process.  Some commands are built-in  purely  for  convenience
       and  are  not documented here.  Built-ins that cause side effects in the shell environment
       and built-ins that are found before performing a path search  (see  Execution  below)  are
       documented  here.  For historical reasons, some of these built-ins behave differently than
       other built-ins and are called special built-ins.

   Commands.
       A simple-command is a list of variable assignments (see Variable Assignments below)  or	a
       sequence  of blank separated words which may be preceded by a list of variable assignments
       (see Environment below).  The first word specifies the name of the command to be executed.
       Except as specified below, the remaining words are passed as arguments to the invoked com-
       mand.  The command name is passed as argument 0 (see exec(2)).  The value of a simple-com-
       mand  is  its  exit  status;  0-255 if it terminates normally; 256+signum if it terminates
       abnormally (the name of the signal corresponding to the exit status can	be  obtained  via
       the -l option of the kill built-in utility).

       A  pipeline  is a sequence of one or more commands separated by |.  The standard output of
       each command but the last is connected by a pipe(2) to the standard input of the next com-
       mand.   Each  command,  except  possibly the last, is run as a separate process; the shell
       waits for the last command to terminate.  The exit status of a pipeline is the exit status
       of  the last command unless the pipefail option is enabled.  Each pipeline can be preceded
       by the reserved word !  which causes the exit status of the pipeline to become  0  if  the
       exit  status of the last command is non-zero, and 1 if the exit status of the last command
       is 0.

       A list is a sequence of one or more pipelines separated by  ;,  &,  |&,	&&,  or  ||,  and
       optionally  terminated  by  ;,  &,  or |&.  Of these five symbols, ;, &, and |& have equal
       precedence, which is lower than that of && and ||.  The symbols && and || also have  equal
       precedence.   A	semicolon  (;)	causes sequential execution of the preceding pipeline; an
       ampersand (&) causes asynchronous execution of the preceding  pipeline  (i.e.,  the  shell
       does  not  wait for that pipeline to finish).  The symbol |& causes asynchronous execution
       of the preceding pipeline with a two-way pipe established to the parent shell;  the  stan-
       dard  input and output of the spawned pipeline can be written to and read from by the par-
       ent shell by applying the redirection operators <& and >& with arg p to	commands  and  by
       using  -p  option  of the built-in commands read and print described later.  The symbol &&
       (||) causes the list following it to be executed only if the preceding pipeline returns	a
       zero (non-zero) value.  One or more new-lines may appear in a list instead of a semicolon,
       to delimit a command.  The first item  of the first pipeline of a list that  is	a  simple
       command	not  beginning with a redirection, and not occurring within a while, until, or if
       list, can be preceded by a semicolon.  This semicolon is ignored unless the showme  option
       is enabled as described with the set built-in below.

       A  command  is  either a simple-command or one of the following.  Unless otherwise stated,
       the value returned by a command is that of the last simple-command executed  in	the  com-
       mand.

       for vname [ in word ... ] ;do list ;done
	      Each  time  a for command is executed, vname is set to the next word taken from the
	      in word list.  If in word ...  is omitted, then the for  command	executes  the  do
	      list  once for each positional parameter that is set starting from 1 (see Parameter
	      Expansion below).  Execution ends when there are no more words in the list.

       for (( [expr1] ; [expr2] ; [expr3] )) ;do list ;done
	      The arithmetic expression expr1  is  evaluated  first  (see  Arithmetic  evaluation
	      below).  The arithmetic expression expr2 is repeatedly evaluated until it evaluates
	      to zero and when non-zero, list is executed and  the  arithmetic	expression  expr3
	      evaluated.  If any expression is omitted, then it behaves as if it evaluated to 1.

       select vname [ in word ... ] ;do list ;done
	      A  select  command  prints  on standard error (file descriptor 2) the set of words,
	      each preceded by a number.  If in word ...  is omitted, then the positional parame-
	      ters  starting  from  1  are used instead (see Parameter Expansion below).  The PS3
	      prompt is printed and a line is read from the standard input.  If  this  line  con-
	      sists  of  the  number  of  one of the listed words, then the value of the variable
	      vname is set to the word corresponding to this number.  If this line is empty,  the
	      selection  list is printed again.  Otherwise the value of the variable vname is set
	      to null.	The contents of the line read from standard input is saved in  the  vari-
	      able  REPLY.   The list is executed for each selection until a break or end-of-file
	      is encountered.  If the REPLY variable is set to null by	the  execution	of  list,
	      then  the  selection  list is printed before displaying the PS3 prompt for the next
	      selection.

       case word in [ [(]pattern [ | pattern ] ... ) list ;; ] ... esac
	      A case command executes the list associated with the  first  pattern  that  matches
	      word.   The  form of the patterns is the same as that used for file-name generation
	      (see File Name Generation below).  The ;; operator causes execution of case to ter-
	      minate.	If  ;&	is used in place of ;; the next subsequent list, if any,  is exe-
	      cuted.

       if list ;then list [ ;elif list ;then list ] ... [ ;else list ] ;fi
	      The list following if is executed and, if it returns a zero exit status,	the  list
	      following  the  first then is executed.  Otherwise, the list following elif is exe-
	      cuted and, if its value is zero, the list following  the	next  then  is	executed.
	      Failing  each  successive elif list, the else list is executed.  If the if list has
	      non-zero exit status and there is no else list, then the if command returns a  zero
	      exit status.

       while list ;do list ;done
       until list ;do list ;done
	      A  while	command repeatedly executes the while list and, if the exit status of the
	      last command in the list is zero, executes the do list; otherwise the  loop  termi-
	      nates.   If no commands in the do list are executed, then the while command returns
	      a zero exit status; until may be used in place of while to negate the loop termina-
	      tion test.

       ((expression))
	      The  expression  is  evaluated  using the rules for arithmetic evaluation described
	      below.  If the value of the arithmetic expression is non-zero, the exit  status  is
	      0, otherwise the exit status is 1.

       (list)
	      Execute  list in a separate environment.	Note, that if two adjacent open parenthe-
	      ses are needed for nesting, a space must be inserted  to	avoid  evaluation  as  an
	      arithmetic command as described above.

       { list;}
	      list  is simply executed.  Note that unlike the metacharacters ( and ), { and } are
	      reserved words and must occur at the beginning of a line or after a ; in	order  to
	      be recognized.

       [[ expression ]]
	      Evaluates  expression  and returns a zero exit status when expression is true.  See
	      Conditional Expressions below, for a description of expression.

       function varname { list ;}
       varname () { list ;}
	      Define a function which is referenced by varname.  A function  whose  varname  con-
	      tains a .  is called a discipline function and the portion of the varname preceding
	      the last .  must refer to an existing variable.  The body of the	function  is  the
	      list  of	commands  between  { and }.  A function defined with the function varname
	      syntax can also be used as an argument to the .  special built-in  command  to  get
	      the  equivalent  behavior  as if the varname() syntax were used to define it.  (See
	      Functions below.)

       namespace identifier { list ;}
	      Defines or uses the name space identifier and runs the commands  in  list  in  this
	      name space.  (See Name Spaces below.)

       & [ name [ arg... ]  ]
	      Causes  subsequent list commands terminated by & to be placed in the background job
	      pool name.  If name is omitted a default unnamed pool is used.  Commands in a named
	      background pool may be executed remotely.

       time [ pipeline ]
	      If pipeline is omitted the user and system time for the current shell and completed
	      child processes is printed on standard error.  Otherwise, pipeline is executed  and
	      the elapsed time as well as the user and system time are printed on standard error.
	      The TIMEFORMAT variable may be set to a format string that specifies how the timing
	      information  should  be  displayed.  See Shell Variables below for a description of
	      the TIMEFORMAT variable.

       The following reserved words are recognized as reserved only when they are the first  word
       of a command and are not quoted:

       if then else elif fi case esac for while until do done { } function select time [[ ]] !

   Variable Assignments.
       One  or	more  variable	assignments can start a simple command or can be arguments to the
       typeset, enum, export, or readonly special built-in commands as well as to other  declara-
       tion commands created as types.	The syntax for an assignment is of the form:

       varname=word
       varname[word]=word
	      No space is permitted between varname and the = or between = and word.

       varname=(assign_list)
	      No  space  is  permitted	between varname and the =.  The variable varname is unset
	      before the assignment.  An assign_list can be one of the following:
		      word ...
			     Indexed array assignment.
		      [word]=word ...
			     Associative array assignment.  If preceded by typeset -a  this  will
			     create an indexed array instead.
		      assignment ...
			     Compound variable assignment.  This creates a compound variable var-
			     name with sub-variables of the form varname.name, where name is  the
			     name  portion  of assignment.  The value of varname will contain all
			     the assignment elements.  Additional assignments made  to	sub-vari-
			     ables of varname will also be displayed as part of the value of var-
			     name.  If no assignments are specified, varname will be  a  compound
			     variable allowing subsequence child elements to be defined.
		      typeset [options] assignment ...
			     Nested  variable  assignment.  Multiple assignments can be specified
			     by separating each of them with a ;.  The previous  value	is  unset
			     before the assignment.  Other declaration commands such as readonly,
			     enum, and other declaration commands can be used in place	of  type-
			     set.
		      . filename
			     Include the assignment commands contained in filename.

       In  addition,  a += can be used in place of the = to signify adding to or appending to the
       previous value.	When += is applied to an arithmetic type, word is evaluated as an  arith-
       metic  expression  and added to the current value.  When applied to a string variable, the
       value defined by word is appended to the value.	For compound  assignments,  the  previous
       value  is  not unset and the new values are appended to the current ones provided that the
       types are compatible.

       The right hand side of a variable assignment undergoes  all  the  expansion  listed  below
       except word splitting, brace expansion, and file name generation.  When the left hand side
       is an assignment is a compound variable and the right hand is the name of a compound vari-
       able,  the compound variable on the right will be copied or appended to the compound vari-
       able on the left.

   Comments.
       A word beginning with # causes that word and all the following characters up to a new-line
       to be ignored.
   Aliasing.
       The  first  word  of each command is replaced by the text of an alias if an alias for this
       word has been defined.  An alias name consists  of  any	number	of  characters	excluding
       metacharacters,	quoting  characters,  file  expansion characters, parameter expansion and
       command substitution characters, the characters / and =.  The replacement string can  con-
       tain  any valid shell script including the metacharacters listed above.	The first word of
       each command in the replaced text, other than  any  that  are  in  the  process	of  being
       replaced, will be tested for aliases.  If the last character of the alias value is a blank
       then the word following the alias will also be checked for  alias  substitution.   Aliases
       can  be	used  to  redefine  built-in commands but cannot be used to redefine the reserved
       words listed above.  Aliases can be created and listed with the alias command and  can  be
       removed with the unalias command.
       Aliasing  is performed when scripts are read, not while they are executed.  Therefore, for
       an alias to take effect, the alias definition command has to be executed before	the  com-
       mand which references the alias is read.
       The following aliases are compiled into the shell but can be unset or redefined:
			   autoload='typeset -fu'
			   command='command  '
			   compound='typeset -C'
			   fc=hist
			   float='typeset -lE'
			   functions='typeset -f'
			   hash='alias -t --'
			   history='hist -l'
			   integer='typeset -li'
			   nameref='typeset -n'
			   nohup='nohup  '
			   r='hist -s'
			   redirect='command exec'
			   source='command .'
			   stop='kill -s STOP'
			   suspend='kill -s STOP $$'
			   times='{ { time;} 2>&1;}'
			   type='whence -v'

   Tilde Substitution.
       After  alias  substitution  is performed, each word is checked to see if it begins with an
       unquoted ~.  For tilde substitution, word also refers to the  word  portion  of	parameter
       expansion (see Parameter Expansion below).  If it does, then the word up to a / is checked
       to see if it matches a user name in the password database (See getpwname(3).)  If a  match
       is  found,  the	~  and	the matched login name are replaced by the login directory of the
       matched user.  If no match is found, the original text is left unchanged.  A ~ by  itself,
       or  in  front  of  a /, is replaced by $HOME.  A ~ followed by a + or - is replaced by the
       value of $PWD and $OLDPWD respectively.

       In addition, when expanding a variable assignment, tilde substitution  is  attempted  when
       the  value  of the assignment begins with a ~, and when a ~ appears after a :.  The : also
       terminates a ~ login name.

   Command Substitution.
       The standard output from a command list enclosed in parentheses preceded by a dollar  sign
       (  $(list) ), or in a brace group preceded by a dollar sign ( ${ list;} ), or in a pair of
       grave accents (``) may be used as part or all of a word; trailing new-lines  are  removed.
       In the second case, the { and } are treated as a reserved words so that { must be followed
       by a blank and } must appear at the beginning of the line or follow a  ;.   In  the  third
       (obsolete) form, the string between the quotes is processed for special quoting characters
       before the command is executed (see Quoting below).  The command substitution $(cat  file)
       can  be	replaced  by the equivalent but faster $(<file).  The command substitution $(n<#)
       will expand to the current byte offset for file descriptor n.  Except for the second form,
       the  command list is run in a subshell so that no side effects are possible.  For the sec-
       ond form, the final } will be recognized as a reserved word after any token.

   Arithmetic Substitution.
       An arithmetic expression enclosed in double parentheses preceded by a dollar sign (  $(())
       ) is replaced by the value of the arithmetic expression within the double parentheses.

   Process Substitution.
       Each  command argument of the form <(list) or >(list) will run process list asynchronously
       connected to some file in /dev/fd if this directory exists, or else  a  fifo  a	temporary
       directory.   The  name  of this file will become the argument to the command.  If the form
       with > is selected then writing on this file will provide input for list.  If <	is  used,
       then  the  file	passed	as  an argument will contain the output of the list process.  For
       example,

	      paste <(cut -f1 file1) <(cut -f3 file2) | tee >(process1) >(process2)

       cuts fields 1 and 3 from the files  file1  and  file2  respectively,  pastes  the  results
       together,  and sends it to the processes process1 and process2, as well as putting it onto
       the standard output.  Note that the file, which is passed as an argument to  the  command,
       is a UNIX pipe(2) so programs that expect to lseek(2) on the file will not work.

       Process	substitution of the form <(list) can also be used with the < redirection operator
       which causes the output of list to be standard  input  or  the  input  for  whatever  file
       descriptor is specified.

   Parameter Expansion.
       A  parameter is a variable, one or more digits, or any of the characters *, @, #, ?, -, $,
       and !.  A variable is denoted by a vname.  To create a variable whose vname contains a  .,
       a  variable  whose  vname  consists of everything before the last . must already exist.	A
       variable has a value and zero or more attributes.  Variables can be  assigned  values  and
       attributes by using the typeset special built-in command.  The attributes supported by the
       shell are described later with the typeset special built-in command.   Exported	variables
       pass values and attributes to the environment.

       The  shell  supports both indexed and associative arrays.  An element of an array variable
       is referenced by a subscript.  A subscript for an indexed array is denoted  by  an  arith-
       metic  expression (see Arithmetic evaluation below) between a [ and a ].  To assign values
       to an indexed array, use vname=(value ...) or set -A vname  value ... .	The value of  all
       non-negative subscripts must be in the range of 0 through 4,194,303.  A negative subscript
       is treated as an offset from the maximum current index +1 so that -1 refers  to	the  last
       element.   Indexed  arrays  can be declared with the -a option to typeset.  Indexed arrays
       need not be declared.  Any reference to a variable with a valid subscript is legal and  an
       array will be created if necessary.

       An  associative	array is created with the -A option to typeset.  A subscript for an asso-
       ciative array is denoted by a string enclosed between [ and ].

       Referencing any array without a subscript is equivalent to referencing the array with sub-
       script 0.

       The value of a variable may be assigned by writing:

	      vname=value [ vname=value ] ...

       or
	      vname[subscript]=value [ vname[subscript]=value ] ...
       Note that no space is allowed before or after the =.
       Attributes  assigned  by the typeset special built-in command apply to all elements of the
       array.  An array element can be a simple variable, a compound variable or an  array  vari-
       able.   An  element  of	an indexed array can be either an indexed array or an associative
       array.  An element of an associative array can also be either.  To refer to an array  ele-
       ment  that  is part of an array element, concatenate the subscript in brackets.	For exam-
       ple, to refer to the foobar element of an associative array that is defined as  the  third
       element of the indexed array, use ${vname[3][foobar]}
       A  nameref  is  a  variable that is a reference to another variable.  A nameref is created
       with the -n attribute of typeset.  The value of the variable at the time  of  the  typeset
       command	becomes  the  variable	that  will be referenced whenever the nameref variable is
       used.  The name of a nameref cannot contain a ..  When a variable or  function  name  con-
       tains  a  .,  and the portion of the name up to the first . matches the name of a nameref,
       the variable referred to is obtained by replacing the nameref portion with the name of the
       variable  referenced  by  the nameref.  If a nameref is used as the index of a for loop, a
       name reference is established for each item in the list.  A nameref provides a  convenient
       way  to	refer  to the variable inside a function whose name is passed as an argument to a
       function.  For example, if the name of a variable is passed as the  first  argument  to	a
       function, the command
	      typeset -n var=$1
       inside  the function causes references and assignments to var to be references and assign-
       ments to the variable whose name has been passed to the function.
       If any of the floating point attributes, -E, -F, or -X, or the integer attribute,  -i,  is
       set for vname, then the value is subject to arithmetic evaluation as described below.
       Positional parameters, parameters denoted by a number, may be assigned values with the set
       special built-in command.  Parameter $0 is set  from  argument  zero  when  the	shell  is
       invoked.
       The character $ is used to introduce substitutable parameters.
       ${parameter}
	      The  shell  reads  all the characters from ${ to the matching } as part of the same
	      word even if it contains braces or metacharacters.   The	value,	if  any,  of  the
	      parameter  is substituted.  The braces are required when parameter is followed by a
	      letter, digit, or underscore that is not to be interpreted as  part  of  its  name,
	      when  the variable name contains a ..  The braces are also required when a variable
	      is subscripted unless it is part of  an  Arithmetic  Expression  or  a  Conditional
	      Expression.   If parameter is one or more digits then it is a positional parameter.
	      A positional parameter of more than one digit  must  be  enclosed  in  braces.   If
	      parameter is * or @, then all the positional parameters, starting with $1, are sub-
	      stituted (separated by a field separator character).  If an array vname  with  last
	      subscript  *  @,	or for index arrays of the form sub1 ..  sub2.	is used, then the
	      value for each of the elements between sub1 and sub2 inclusive (or all elements for
	      * and @) is substituted, separated by the first character of the value of IFS.
       ${#parameter}
	      If parameter is * or @, the number of positional parameters is substituted.  Other-
	      wise, the length of the value of the parameter is substituted.
       ${#vname[*]}
       ${#vname[@]}
	      The number of elements in the array vname is substituted.

       ${@vname}
	      Expands to the type name (See Type Variables  below) or attributes of the  variable
	      referred to by vname.
       ${!vname}
	      Expands  to  the	name  of  the  variable referred to by vname.  This will be vname
	      except when vname is a name reference.
       ${!vname[subscript]}
	      Expands to name of the subscript unless subscript is *, @.  or of the form sub1  ..
	      sub2.   When  subscript  is *, the list of array subscripts for vname is generated.
	      For a variable that is not an array, the value is 0 if the variable is set.  Other-
	      wise it is null.	When subscript is @, same as above, except that when used in dou-
	      ble quotes, each array subscript yields a separate argument.  When subscript is  of
	      the  form  sub1 ..  sub2 it expands to the list of subscripts between sub1 and sub2
	      inclusive using the same quoting rules as @.
       ${!prefix*}
	      Expands to the names of the variables whose names begin with prefix.
       ${parameter:-word}
	      If parameter is set and is non-null then substitute its value; otherwise substitute
	      word.
       ${parameter:=word}
	      If  parameter is not set or is null then set it to word; the value of the parameter
	      is then substituted.  Positional parameters may not be assigned to in this way.
       ${parameter:?word}
	      If parameter is set and is non-null then substitute  its	value;	otherwise,  print
	      word and exit from the shell (if not interactive).  If word is omitted then a stan-
	      dard message is printed.
       ${parameter:+word}
	      If parameter is set and is non-null  then  substitute  word;  otherwise  substitute
	      nothing.
       In  the above, word is not evaluated unless it is to be used as the substituted string, so
       that, in the following example, pwd is executed only if d is not set or is null:
	      print ${d:-$(pwd)}
       If the colon ( : ) is omitted from the above  expressions,  then  the  shell  only  checks
       whether parameter is set or not.
       ${parameter:offset:length}
       ${parameter:offset}
	      Expands  to the portion of the value of parameter starting at the character (count-
	      ing from 0) determined by expanding offset as an arithmetic expression and consist-
	      ing  of the number of characters determined by the arithmetic expression defined by
	      length.  In the second form, the remainder of the value is  used.   If  A  negative
	      offset counts backwards from the end of parameter.  Note that one or more blanks is
	      required in front of a minus sign to prevent the shell from interpreting the opera-
	      tor  as  :-.   If  parameter is * or @, or is an array name indexed by * or @, then
	      offset and length refer to the array index and number of elements respectively.	A
	      negative	offset	is  taken  relative to one greater than the highest subscript for
	      indexed arrays.  The order for associate arrays is unspecified.
       ${parameter#pattern}
       ${parameter##pattern}
	      If the shell pattern matches the beginning of the  value	of  parameter,	then  the
	      value  of  this  expansion  is  the value of the parameter with the matched portion
	      deleted; otherwise the value of this parameter is substituted.  In the  first  form
	      the  smallest matching pattern is deleted and in the second form the largest match-
	      ing pattern is deleted.  When parameter is @, *, or an  array  variable  with  sub-
	      script @ or *, the substring operation is applied to each element in turn.

       ${parameter%pattern}
       ${parameter%%pattern}
	      If  the  shell pattern matches the end of the value of parameter, then the value of
	      this expansion is the value of the parameter with the matched part deleted;  other-
	      wise  substitute	the  value of parameter.  In the first form the smallest matching
	      pattern is deleted and in the second form the largest matching pattern is  deleted.
	      When  parameter  is @, *, or an array variable with subscript @ or *, the substring
	      operation is applied to each element in turn.

       ${parameter/pattern/string}
       ${parameter//pattern/string}
       ${parameter/#pattern/string}
       ${parameter/%pattern/string}
	      Expands parameter and replaces the longest match of pattern with the given  string.
	      Each  occurrence	of  \n	in  string  is	replaced by the portion of parameter that
	      matches the n-th sub-pattern.  In the first form, only the first occurrence of pat-
	      tern  is	replaced.   In the second form, each match for pattern is replaced by the
	      given string.  The third form restricts the pattern match to the beginning  of  the
	      string  while the fourth form restricts the pattern match to the end of the string.
	      When string is null, the pattern will be deleted and the / in front of  string  may
	      be  omitted.   When  parameter is @, *, or an array variable with subscript @ or *,
	      the substitution operation is applied to each element in turn.  In this  case,  the
	      string portion of word will be re-evaluated for each element.

       The following parameters are automatically set by the shell:
	      #      The number of positional parameters in decimal.
	      -      Options supplied to the shell on invocation or by the set command.
	      ?      The decimal value returned by the last executed command.
	      $      The process number of this shell.
	      _      Initially,  the  value  of  _ is an absolute pathname of the shell or script
		     being executed as passed in the environment.  Subsequently  it  is  assigned
		     the  last	argument  of the previous command.  This parameter is not set for
		     commands which are asynchronous.  This parameter is also used  to	hold  the
		     name  of  the  matching  MAIL file when checking for mail.  While defining a
		     compound variable or a type, _ is initialized as a reference to the compound
		     variable  or  type.  When a discipline function is invoked, _ is initialized
		     as a reference to the variable associated with the call  to  this	function.
		     Finally  when  _ is used as the name of the first variable of a type defini-
		     tion, the new type is derived from the type of the first variable (See  Type
		     Variables	below.).
	      !      The  process  id or the pool name and job number of the last background com-
		     mand invoked or the most recent job put in the background with the bg built-
		     in  command.   Background	jobs  started in a named pool will be in the form
		     pool.number where pool is the pool name and number is the job number  within
		     that pool.
	      .sh.command
		     When  processing  a  DEBUG  trap, this variable contains the current command
		     line that is about to run.
	      .sh.edchar
		     This variable contains the value of the keyboard character (or  sequence  of
		     characters  if  the  first  character  is	an  ESC, ascii 033) that has been
		     entered when processing a KEYBD trap (see Key Bindings below).  If the value
		     is  changed  as part of the trap action, then the new value replaces the key
		     (or key sequence) that caused the trap.
	      .sh.edcol
		     The character position of the cursor at the time of the  most  recent  KEYBD
		     trap.
	      .sh.edmode
		     The  value  is  set  to  ESC when processing a KEYBD trap while in vi insert
		     mode.  (See Vi Editing Mode  below.)  Otherwise,  .sh.edmode  is  null  when
		     processing a KEYBD trap.
	      .sh.edtext
		     The  characters  in  the  input  buffer at the time of the most recent KEYBD
		     trap.  The value is null when not processing a KEYBD trap.
	      .sh.file
		     The pathname of the file than contains the current command.
	      .sh.fun
		     The name of the current function that is being executed.
	      .sh.level
		     Set to the current function depth.  This can be changed inside a DEBUG  trap
		     and will set the context to the specified level.
	      .sh.lineno
		     Set during a DEBUG trap to the line number for the caller of each function.
	      .sh.match
		     An  indexed array which stores the most recent match and sub-pattern matches
		     after conditional pattern matches that match and after variables  expansions
		     using  the operators #, %, or /.  The 0-th element stores the complete match
		     and the i-th.  element stores the i-th  submatch.	 The  .sh.match  variable
		     becomes unset when the variable that has expanded is assigned a new value.
	      .sh.math
		     Used  for	defining  arithmetic functions (see Arithmetic evaluation below).
		     and stores the list of user defined arithmetic functions.
	      .sh.name
		     Set to the name of the variable at the time that a  discipline  function  is
		     invoked.
	      .sh.subscript
		     Set  to  the  name  subscript  of the variable at the time that a discipline
		     function is invoked.
	      .sh.subshell
		     The current depth for subshells and command substitution.
	      .sh.value
		     Set to the value of the variable at the time that the set or  append  disci-
		     pline  function  is  invoked.   When  a  user defined arithmetic function is
		     invoked, the value of .sh.value is saved and .sh.value is set to long double
		     precision floating point.	.sh.value is restored when the function returns.
	      .sh.version
		     Set to a value that identifies the version of this shell.
	      KSH_VERSION
		     A name reference to .sh.version.
	      LINENO The current line number within the script or function being executed.
	      OLDPWD The previous working directory set by the cd command.
	      OPTARG The value of the last option argument processed by the getopts built-in com-
		     mand.
	      OPTIND The index of the last option argument processed by the getopts built-in com-
		     mand.
	      PPID   The process number of the parent of the shell.
	      PWD    The present working directory set by the cd command.
	      RANDOM Each  time this variable is referenced, a random integer, uniformly distrib-
		     uted between 0 and 32767, is generated.  The sequence of random numbers  can
		     be initialized by assigning a numeric value to RANDOM.
	      REPLY  This  variable  is set by the select statement and by the read built-in com-
		     mand when no arguments are supplied.
	      SECONDS
		     Each time this variable is referenced, the number	of  seconds  since  shell
		     invocation  is  returned.	 If  this  variable is assigned a value, then the
		     value returned upon reference will be the value that was assigned	plus  the
		     number of seconds since the assignment.
	      SHLVL  An integer variable the is incremented each time the shell is invoked and is
		     exported.	If SHLVL is not in the environment when the shell is invoked,  it
		     is set to 1.

       The following variables are used by the shell:
	      CDPATH The search path for the cd command.
	      COLUMNS
		     If  this  variable is set, the value is used to define the width of the edit
		     window for the shell edit modes and for printing select lists.
	      EDITOR If the VISUAL variable is not set,  the  value  of  this  variable  will  be
		     checked  for the patterns as described with VISUAL below and the correspond-
		     ing editing option (see Special Command set below) will be turned on.
	      ENV    If this variable is set, then parameter expansion, command substitution, and
		     arithmetic  substitution are performed on the value to generate the pathname
		     of the script that will be executed when the shell is invoked  interactively
		     (see  Invocation below).  This file is typically used for alias and function
		     definitions.  The default value is $HOME/.kshrc.  On systems that support	a
		     system  wide   /etc/ksh.kshrc initialization file, if the filename generated
		     by the expansion of ENV begins with /./ or ././ the system wide  initializa-
		     tion file will not be executed.
	      FCEDIT Obsolete  name  for the default editor name for the hist command.	FCEDIT is
		     not used when HISTEDIT is set.
	      FIGNORE
		     A pattern that defines the set of filenames that will be ignored  when  per-
		     forming filename matching.
	      FPATH  The  search path for function definitions.  The directories in this path are
		     searched for a file with the same name as the function  or  command  when	a
		     function  with  the  -u  attribute  is  referenced and when a command is not
		     found.  If an executable file with the name of that command is  found,  then
		     it  is  read and executed in the current environment.  Unlike PATH, the cur-
		     rent directory must be represented explicitly by .  rather than by  adjacent
		     : characters or a beginning or ending :.
	      HISTCMD
		     Number of the current command in the history file.
	      HISTEDIT
		     Name for the default editor name for the hist command.
	      HISTFILE
		     If  this  variable  is  set when the shell is invoked, then the value is the
		     pathname of the file that will be used to store  the  command  history  (see
		     Command Re-entry below).
	      HISTSIZE
		     If this variable is set when the shell is invoked, then the number of previ-
		     ously entered commands that are accessible by this  shell	will  be  greater
		     than or equal to this number.  The default is 512.
	      HOME   The default argument (home directory) for the cd command.
	      IFS    Internal  field  separators, normally space, tab, and new-line that are used
		     to separate the results of command substitution or parameter  expansion  and
		     to  separate  fields with the built-in command read.  The first character of
		     the IFS variable is used to separate arguments  for  the  "$*"  substitution
		     (see  Quoting  below).   Each  single  occurrence of an IFS character in the
		     string to be split, that is not in the  isspace  character  class,  and  any
		     adjacent  characters in IFS that are in the isspace character class, delimit
		     a field.  One or more characters in IFS that belong to the isspace character
		     class,  delimit a field.  In addition, if the same isspace character appears
		     consecutively inside IFS, this character is treated as if it were not in the
		     isspace class, so that if IFS consists of two tab characters, then two adja-
		     cent tab characters delimit a null field.
	      JOBMAX This variable defines the maximum number running background  jobs	that  can
		     run at a time.  When this limit is reached, the shell will wait for a job to
		     complete before staring a new job.
	      LANG   This variable determines the locale category for any category  not  specifi-
		     cally selected with a variable starting with LC_ or LANG.
	      LC_ALL This  variable  overrides	the  value of the LANG variable and any other LC_
		     variable.
	      LC_COLLATE
		     This variable determines the locale category for character collation  infor-
		     mation.
	      LC_CTYPE
		     This  variable  determines  the locale category for character handling func-
		     tions.  It determines the character classes for pattern matching  (see  File
		     Name Generation below).
	      LC_NUMERIC
		     This  variable  determines the locale category for the decimal point charac-
		     ter.
	      LINES  If this variable is set, the value is used to determine  the  column  length
		     for  printing  select lists.  Select lists will print vertically until about
		     two-thirds of LINES lines are filled.
	      MAIL   If this variable is set to the name of a mail file and the MAILPATH variable
		     is not set, then the shell informs the user of arrival of mail in the speci-
		     fied file.
	      MAILCHECK
		     This variable specifies how often (in seconds)  the  shell  will  check  for
		     changes  in the modification time of any of the files specified by the MAIL-
		     PATH or MAIL variables.  The default value is 600 seconds.   When	the  time
		     has elapsed the shell will check before issuing the next prompt.
	      MAILPATH
		     A	colon  ( : ) separated list of file names.  If this variable is set, then
		     the shell informs the user of any modifications to the specified files  that
		     have occurred within the last MAILCHECK seconds.  Each file name can be fol-
		     lowed by a ?  and a message that will be printed.	The message will  undergo
		     parameter	expansion, command substitution, and arithmetic substitution with
		     the variable $_ defined as the name of  the  file	that  has  changed.   The
		     default message is you have mail in $_.
	      PATH   The search path for commands (see Execution below).  The user may not change
		     PATH if executing under rksh (except in .profile).
	      PS1    The value of this variable is expanded for parameter expansion, command sub-
		     stitution,  and  arithmetic substitution to define the primary prompt string
		     which by default is ``$''.  The character !  in the primary prompt string is
		     replaced by the command number (see Command Re-entry below).  Two successive
		     occurrences of !  will produce  a	single	!   when  the  prompt  string  is
		     printed.
	      PS2    Secondary prompt string, by default ``> ''.
	      PS3    Selection prompt string used within a select loop, by default ``#? ''.
	      PS4    The  value  of  this  variable is expanded for parameter evaluation, command
		     substitution, and arithmetic substitution and precedes each line of an  exe-
		     cution  trace.   By  default, PS4 is ``+ ''.  In addition when PS4 is unset,
		     the execution trace prompt is also ``+ ''.
	      SHELL  The pathname of the shell is kept in the environment.  At invocation, if the
		     basename  of  this  variable  is  rsh, rksh, or krsh, then the shell becomes
		     restricted.  If it is pfsh or pfksh, then the shell becomes a profile  shell
		     (see pfexec(1)).
	      TIMEFORMAT
		     The  value  of  this parameter is used as a format string specifying how the
		     timing information for pipelines prefixed with the time reserved word should
		     be displayed.  The % character introduces a format sequence that is expanded
		     to a time value or other information.  The format sequences and their  mean-
		     ings are as follows.
		     %%        A literal %.
		     %[p][l]R  The elapsed time in seconds.
		     %[p][l]U  The number of CPU seconds spent in user mode.
		     %[p][l]S  The number of CPU seconds spent in system mode.
		     %P        The CPU percentage, computed as (U + S) / R.

		     The brackets denote optional portions.  The optional p is a digit specifying
		     the precision, the number of fractional digits after  a  decimal  point.	A
		     value  of 0 causes no decimal point or fraction to be output.  At most three
		     places after the decimal point can be displayed; values of p greater than	3
		     are treated as 3.	If p is not specified, the value 3 is used.

		     The  optional  l  specifies a longer format, including hours if greater than
		     zero, minutes, and seconds of the form HHhMMmSS.FFs.  The value of p  deter-
		     mines whether or not the fraction is included.

		     All  other  characters  are  output without change and a trailing newline is
		     added.  If unset, the default  value,  $'\nreal\t%2lR\nuser\t%2lU\nsys%2lS',
		     is used.  If the value is null, no timing information is displayed.

	      TMOUT  If set to a value greater than zero, TMOUT will be the default timeout value
		     for the read built-in command.  The select compound command terminates after
		     TMOUT seconds when input is from a terminal.  Otherwise, the shell will ter-
		     minate if a line is not entered within  the  prescribed  number  of  seconds
		     while  reading from a terminal.  (Note that the shell can be compiled with a
		     maximum bound for this value which cannot be exceeded.)

	      VISUAL If the value of this variable matches the pattern *[Vv][Ii]*,  then  the  vi
		     option  (see  Special Command set below) is turned on.  If the value matches
		     the pattern *gmacs* , the gmacs option is turned on.  If the  value  matches
		     the  pattern  *macs*, then the emacs option will be turned on.  The value of
		     VISUAL overrides the value of EDITOR.

       The shell gives default values to PATH, PS1, PS2, PS3, PS4, MAILCHECK, FCEDIT,  TMOUT  and
       IFS,  while  HOME,  SHELL, ENV, and MAIL are not set at all by the shell (although HOME is
       set by login(1)).  On some systems MAIL and SHELL are also set by login(1).

   Field Splitting.
       After parameter expansion and command  substitution,  the  results  of  substitutions  are
       scanned	for  the  field separator characters (those found in IFS) and split into distinct
       fields where such characters are found.	Explicit null fields (""  or  '')  are	retained.
       Implicit  null fields (those resulting from parameters that have no values or command sub-
       stitutions with no output) are removed.

       If the braceexpand (-B) option is set then each of  the	fields	resulting  from  IFS  are
       checked	to  see  if  they  contain  one  or  more of the brace patterns {*,*}, {l1..l2} ,
       {n1..n2} , {n1..n2% fmt} , {n1..n2 ..n3} , or {n1..n2 ..n3%fmt} , where *  represents  any
       character, l1,l2 are letters and n1,n2,n3 are signed numbers and fmt is a format specified
       as used by printf.  In each case, fields are created by prepending the  characters  before
       the  {  and  appending  the characters after the } to each of the strings generated by the
       characters between the { and }.	The resulting fields are checked to see if they have  any
       brace patterns.

       In  the	first  form, a field is created for each string between { and ,, between , and ,,
       and between , and }.  The string represented by * can contain embedded matching	{  and	}
       without quoting.  Otherwise, each { and } with * must be quoted.

       In  the seconds form, l1 and l2 must both be either upper case or both be lower case char-
       acters in the C locale.	In this case a field is created for each character from  l1  thru
       l2.

       In  the	remaining forms, a field is created for each number starting at n1 and continuing
       until it reaches n2 incrementing n1 by n3.  The cases where n3 is not specified behave  as
       if  n3  where 1 if n1<=n2 and -1 otherwise.  If forms which specify %fmt any format flags,
       widths and precisions can be specified and fmt can end in any of the  specifiers  cdiouxX.
       For  example,  {a,z}{1..5..3%02d}{b..c}x  expands  to  the  8 fields, a01bx, a01cx, a04bx,
       a04cx, z01bx, z01cx, z04bx and z4cx.

   File Name Generation.
       Following splitting, each field is scanned for the characters *, ?, (, and [ unless the -f
       option  has  been set.  If one of these characters appears, then the word is regarded as a
       pattern.  Each file name component that contains any pattern character is replaced with	a
       lexicographically sorted set of names that matches the pattern from that directory.  If no
       file name is found that matches the pattern, then that component of the filename  is  left
       unchanged  unless  the  pattern	is  prefixed  with  ~(N)  in  which case it is removed as
       described below.  If FIGNORE is set, then each file name component that matches	the  pat-
       tern  defined  by  the value of FIGNORE is ignored when generating the matching filenames.
       The names .  and ..  are also ignored.  If FIGNORE is not set, the  character  .   at  the
       start  of  each file name component will be ignored unless the first character of the pat-
       tern corresponding to this component is the character .	itself.   Note,  that  for  other
       uses of pattern matching the / and .  are not treated specially.

	      *      Matches  any  string,  including  the  null  string.  When used for filename
		     expansion, if the globstar option is on, two adjacent  *'s  by  itself  will
		     match  all  files	and zero or more directories and subdirectories.  If fol-
		     lowed by a / then only directories and subdirectories will match.
	      ?      Matches any single character.
	      [...]  Matches any one of the enclosed characters.  A pair of characters	separated
		     by  -  matches  any character lexically between the pair, inclusive.  If the
		     first character following the opening [ is a !  or ^ then any character  not
		     enclosed is matched.  A - can be included in the character set by putting it
		     as the first or last character.
		     Within [ and ], character classes can be specified with the syntax [:class:]
		     where  class is one of the following classes defined in the ANSI-C standard:
		     (Note that word is equivalent to alnum plus the character _.)
		     alnum alpha blank cntrl digit graph  lower  print	punct  space  upper  word
		     xdigit
		     Within  [ and ], an equivalence class can be specified with the syntax [=c=]
		     which matches all characters with the  same  primary  collation  weight  (as
		     defined  by  the current locale) as the character c.  Within [ and ], [.sym-
		     bol.]  matches the collating symbol symbol.
       A pattern-list is a list of one or more patterns separated from each other with a & or  |.
       A  &  signifies that all patterns must be matched whereas | requires that only one pattern
       be matched.  Composite patterns can be formed with one or more of the  following  sub-pat-
       terns:
	      ?(pattern-list)
		     Optionally matches any one of the given patterns.
	      *(pattern-list)
		     Matches zero or more occurrences of the given patterns.
	      +(pattern-list)
		     Matches one or more occurrences of the given patterns.
	      {n}(pattern-list)
		     Matches n occurrences of the given patterns.
	      {m,n}(pattern-list)
		     Matches  from  m to n occurrences of the given patterns.  If m is omitted, 0
		     will be used.  If n is omitted at least m occurrences will be matched.
	      @(pattern-list)
		     Matches exactly one of the given patterns.
	      !(pattern-list)
		     Matches anything except one of the given patterns.
       By default, each pattern, or sub-pattern will match the longest string possible consistent
       with  generating  the  longest overall match.  If more than one match is possible, the one
       starting closest to the beginning of the string will be chosen.	 However, for each of the
       above  compound patterns a - can be inserted in front of the ( to cause the shortest match
       to the specified pattern-list to be used.

       When pattern-list is contained within parentheses, the backslash character  \  is  treated
       specially  even	when  inside a character class.   All ANSI-C character escapes are recog-
       nized and match the specified character.  In addition the following escape  sequences  are
       recognized:
	      \d     Matches any character in the digit class.
	      \D     Matches any character not in the digit class.
	      \s     Matches any character in the space class.
	      \S     Matches any character not in the space class.
	      \w     Matches any character in the word class.
	      \W     Matches any character not in the word class.

       A pattern of the form %(pattern-pair(s)) is a sub-pattern that can be used to match nested
       character expressions.  Each pattern-pair is a two character sequence which cannot contain
       &  or  |.   The	first  pattern-pair  specifies the starting and ending characters for the
       match.  Each subsequent pattern-pair represents the beginning and ending characters  of	a
       nested  group  that  will  be  skipped  over  when  counting starting and ending character
       matches.  The behavior is unspecified when the first character of a pattern-pair is alpha-
       numeric except for the following:
	      D      Causes the ending character to terminate the search for this pattern without
		     finding a match.
	      E      Causes the ending character to be interpreted as an escape character.
	      L      Causes the ending character to be interpreted as a quote  character  causing
		     all characters to be ignored when looking for a match.
	      Q      Causes  the  ending character to be interpreted as a quote character causing
		     all characters other than any escape character to be  ignored  when  looking
		     for a match.
       Thus, %({}Q"E\), matches characters starting at { until the matching } is found not count-
       ing any { or } that is inside a double quoted string or preceded by the	escape	character
       \.  Without the {} this pattern matches any C language string.

       Each sub-pattern in a composite pattern is numbered, starting at 1, by the location of the
       ( within the pattern.  The sequence \n, where n is a single digit and \n comes  after  the
       n-th. sub-pattern, matches the same string as the sub-pattern itself.

       Finally	a  pattern  can  contain  sub-patterns of the form ~(options:pattern-list), where
       either options or :pattern-list can be omitted.	Unlike the other compound patterns, these
       sub-patterns  are not counted in the numbered sub-patterns.  :pattern-list must be omitted
       for options F, G, N , and V below.  If options is present, it can consist of one  or  more
       of the following:
	      +      Enable the following options.  This is the default.
	      -      Disable the following options.
	      E      The  remainder  of  the pattern uses extended regular expression syntax like
		     the egrep(1) command.
	      F      The remainder of the pattern uses fgrep(1) expression syntax.
	      G      The remainder of the pattern uses basic regular expression syntax	like  the
		     grep(1) command.
	      K      The  remainder  of  the  pattern  uses  shell  pattern  syntax.  This is the
		     default.
	      N      This is ignored.  However, when it is the first letter and is used with file
		     name generation, and no matches occur, the file pattern expands to the empty
		     string.
	      X      The remainder of the pattern uses augmented regular expression  syntax  like
		     the xgrep(1) command.
	      P      The  remainder  of  the pattern uses perl(1) regular expression syntax.  Not
		     all perl regular expression syntax is currently implemented.
	      V      The remainder of the pattern uses System V regular expression syntax.
	      i      Treat the match as case insensitive.
	      g      File the longest match (greedy).  This is the default.
	      l      Left anchor the pattern.  This is the default for K style patterns.
	      r      Right anchor the pattern.	This is the default for K style patterns.
       If both options and :pattern-list are specified, then the options apply only to	 pattern-
       list.   Otherwise,  these options remain in effect until they are disabled by a subsequent
       ~(...) or at the end of the sub-pattern containing ~(...).

   Quoting.
       Each of the metacharacters listed earlier (see Definitions above) has a special meaning to
       the  shell  and	causes	termination  of  a word unless quoted.	A character may be quoted
       (i.e., made to stand for itself) by preceding it with a \.  The pair \new-line is removed.
       All  characters enclosed between a pair of single quote marks ('') that is not preceded by
       a $ are quoted.	A single quote cannot appear within the single quotes.	A  single  quoted
       string  preceded  by an unquoted $ is processed as an ANSI-C string except for the follow-
       ing:
       \0     Causes the remainder of the string to be ignored.
       \E     Equivalent to the escape character (ascii 033),
       \e     Equivalent to the escape character (ascii 033),
       \cx    Expands to the character control-x.
       \C[.name.]
	      Expands to the collating element name.

       Inside double quote marks (""), parameter and command substitution occur and \ quotes  the
       characters  \, `, ", and $.  A $ in front of a double quoted string will be ignored in the
       "C" or "POSIX" locale, and may cause the string to be replaced by a locale specific string
       otherwise.   The meaning of $* and $@ is identical when not quoted or when used as a vari-
       able assignment value or as a file name.  However, when used as a command  argument,  "$*"
       is  equivalent to "$1d$2d...", where d is the first character of the IFS variable, whereas
       "$@" is equivalent to "$1" "$2" ....  Inside grave quote marks (``), \ quotes the  charac-
       ters  \, `, and $.  If the grave quotes occur within double quotes, then \ also quotes the
       character ".

       The special meaning of reserved words or aliases can be removed by quoting  any	character
       of  the reserved word.  The recognition of function names or built-in command names listed
       below cannot be altered by quoting them.

   Arithmetic Evaluation.
       The shell performs arithmetic evaluation  for  arithmetic  substitution,  to  evaluate  an
       arithmetic  command,  to evaluate an indexed array subscript, and to evaluate arguments to
       the built-in commands shift and let.  Evaluations are  performed  using	double	precision
       floating point arithmetic or long double precision floating point for systems that provide
       this data type.	Floating point constants follow the ANSI-C programming language  floating
       point  conventions.  The floating point constants Nan and Inf can be use to represent "not
       a number" and infinity respectively.  Integer constants follow the ANSI-C programming lan-
       guage  integer constant conventions although only single byte character constants are rec-
       ognized and character casts are not recognized.	In addition constants can be of the  form
       [base#]n where base is a decimal number between two and sixty-four representing the arith-
       metic base and n is a number in that base.  The digits above  9	are  represented  by  the
       lower case letters, the upper case letters, @, and _ respectively.  For bases less than or
       equal to 36, upper and lower case characters can be used interchangeably.

       An arithmetic expression uses the same syntax, precedence, and associativity of expression
       as  the	C language.  All the C language operators that apply to floating point quantities
       can be used.  In addition, the operator ** can be used for exponentiation.  It has  higher
       precedence than multiplication and is left associative.	In addition, when the value of an
       arithmetic variable or sub-expression can be represented as a long integer, all C language
       integer	arithmetic  operations	can  be  performed.   Variables can be referenced by name
       within an arithmetic expression without using the  parameter  expansion	syntax.   When	a
       variable is referenced, its value is evaluated as an arithmetic expression.

       Any  of	the  following	math library functions that are in the C math library can be used
       within an arithmetic expression:

       abs acos acosh asin asinh atan atan2 atanh cbrt ceil copysign cos cosh erf erfc	exp  exp2
       expm1  fabs  fpclassify fdim finite floor fma fmax fmin fmod hypot ilogb int isfinite sinf
       isnan isnormal issubnormal issubordered iszero j0 j1 jn lgamma log log10 log2  logb  near-
       byint  nextafter  nexttoward pow remainder rint round scanb signbit sin sinh sqrt tan tanh
       tgamma trunc y0 y1 yn In addition, arithmetic functions can be define as  shell	functions
       with a variant of the function name syntax,

       function .sh.math.name ident ... { list ;}
	      where  name is the function name used in the arithmetic expression and each identi-
	      fier, ident is a name reference to the long double precision floating  point  argu-
	      ment.   The value of .sh.value when the function returns is the value of this func-
	      tion.  User defined functions can take up  to  3	arguments  and	override  C  math
	      library functions.

       An internal representation of a variable as a double precision floating point can be spec-
       ified with the -E [n], -F [n], or -X [n] option of the typeset special  built-in  command.
       The  -E	option causes the expansion of the value to be represented using scientific nota-
       tion when it is expanded.  The optional option argument n defines the number  of  signifi-
       cant  figures.  The -F option causes the expansion to be represented as a floating decimal
       number when it is expanded.  The -X option cause the expansion to be represented using the
       %a  format  defined  by	ISO  C-99.   The optional option argument n defines the number of
       places after the decimal (or radix) point in this case.

       An internal integer representation of a variable can be specified with the -i  [n]  option
       of  the	typeset  special  built-in  command.  The optional option argument n specifies an
       arithmetic base to be used when expanding the variable.	If you do not specify  an  arith-
       metic base, base 10 will be used.

       Arithmetic  evaluation is performed on the value of each assignment to a variable with the
       -E, -F, -X, or -i attribute.  Assigning a floating point number to a variable  whose  type
       is an integer causes the fractional part to be truncated.

   Prompting.
       When  used  interactively,  the shell prompts with the value of PS1 after expanding it for
       parameter expansion, command substitution, and arithmetic substitution, before  reading	a
       command.   In addition, each single !  in the prompt is replaced by the command number.	A
       !!  is required to place !  in the prompt.  If at any time a new-line is typed and further
       input  is needed to complete a command, then the secondary prompt (i.e., the value of PS2)
       is issued.

   Conditional Expressions.
       A conditional expression is used with the [[ compound command to test attributes of  files
       and to compare strings.	Field splitting and file name generation are not performed on the
       words between [[ and ]].  Each expression can be constructed from one or more of the  fol-
       lowing unary or binary expressions:
       string True, if string is not null.
       -a file
	      Same as -e below.  This is obsolete.
       -b file
	      True, if file exists and is a block special file.
       -c file
	      True, if file exists and is a character special file.
       -d file
	      True, if file exists and is a directory.
       -e file
	      True, if file exists.
       -f file
	      True, if file exists and is an ordinary file.
       -g file
	      True, if file exists and it has its setgid bit set.
       -k file
	      True, if file exists and it has its sticky bit set.
       -n string
	      True, if length of string is non-zero.
       -o ?option
	      True, if option named option is a valid option name.
       -o option
	      True, if option named option is on.
       -p file
	      True, if file exists and is a fifo special file or a pipe.
       -r file
	      True, if file exists and is readable by current process.
       -s file
	      True, if file exists and has size greater than zero.
       -t fildes
	      True,  if  file  descriptor  number  fildes  is open and associated with a terminal
	      device.
       -u file
	      True, if file exists and it has its setuid bit set.
       -v name
	      True, if variable name is a valid variable name and is set.
       -w file
	      True, if file exists and is writable by current process.
       -x file
	      True, if file exists and is executable by current process.  If file exists and is a
	      directory,  then true if the current process has permission to search in the direc-
	      tory.
       -z string
	      True, if length of string is zero.
       -L file
	      True, if file exists and is a symbolic link.
       -h file
	      True, if file exists and is a symbolic link.
       -N file
	      True, if file exists and the modification time is  greater  than	the  last  access
	      time.
       -O file
	      True, if file exists and is owned by the effective user id of this process.
       -G file
	      True, if file exists and its group matches the effective group id of this process.
       -R name
	      True if variable name is a name reference.
       -S file
	      True, if file exists and is a socket.
       file1 -nt file2
	      True, if file1 exists and file2 does not, or file1 is newer than file2.
       file1 -ot file2
	      True, if file2 exists and file1 does not, or file1 is older than file2.
       file1 -ef file2
	      True, if file1 and file2 exist and refer to the same file.
       string == pattern
	      True,  if string matches pattern.  Any part of pattern can be quoted to cause it to
	      be matched as a string.  With a successful match to a pattern, the .sh.match  array
	      variable will contain the match and sub-pattern matches.
       string = pattern
	      Same as == above, but is obsolete.
       string != pattern
	      True,  if  string  does not match pattern.  When the string matches the pattern the
	      .sh.match array variable will contain the match and sub-pattern matches.
       string =~ ere
	      True if string matches the pattern ~(E)ere where ere is an extended regular expres-
	      sion.
       string1 < string2
	      True, if string1 comes before string2 based on ASCII value of their characters.
       string1 > string2
	      True, if string1 comes after string2 based on ASCII value of their characters.
       The following obsolete arithmetic comparisons are also permitted:
       exp1 -eq exp2
	      True, if exp1 is equal to exp2.
       exp1 -ne exp2
	      True, if exp1 is not equal to exp2.
       exp1 -lt exp2
	      True, if exp1 is less than exp2.
       exp1 -gt exp2
	      True, if exp1 is greater than exp2.
       exp1 -le exp2
	      True, if exp1 is less than or equal to exp2.
       exp1 -ge exp2
	      True, if exp1 is greater than or equal to exp2.

       In each of the above expressions, if file is of the form /dev/fd/n, where n is an integer,
       then the test is applied to the open file whose descriptor number is n.

       A compound expression can be constructed from these primitives by using any of the follow-
       ing, listed in decreasing order of precedence.
       (expression)
	      True, if expression is true.  Used to group expressions.
       ! expression
	      True if expression is false.
       expression1 && expression2
	      True, if expression1 and expression2 are both true.
       expression1 || expression2
	      True, if either expression1 or expression2 is true.

   Input/Output.
       Before a command is executed, its input and output may be redirected using a special nota-
       tion interpreted by the shell.  The following may appear anywhere in a  simple-command  or
       may  precede  or  follow  a command and are not passed on to the invoked command.  Command
       substitution, parameter expansion, and arithmetic substitution occur before word or  digit
       is  used except as noted below.	File name generation occurs only if the shell is interac-
       tive and the pattern matches a single file.  Field splitting is not performed.

       In each of the following  redirections,	if  file  is  of  the  form  /dev/sctp/host/port,
       /dev/tcp/host/port,  or	/dev/udp/host/port, where host is a hostname or host address, and
       port is a service given by name or an integer port number, then the  redirection  attempts
       to make a tcp, sctp or udp connection to the corresponding socket.

       No intervening space is allowed between the characters of redirection operators.

       <word	     Use file word as standard input (file descriptor 0).

       >word	     Use  file word as standard output (file descriptor 1).  If the file does not
		     exist then it is created.	If the file exists, and the noclobber  option  is
		     on, this causes an error; otherwise, it is truncated to zero length.

       >|word	     Same as >, except that it overrides the noclobber option.

       >;word	     Write  output  to	a  temporary file.  If the command completes successfully
		     rename it to word, otherwise, delete the temporary file.  >;word  cannot  be
		     used with the exec(2).  built-in.

       >>word	     Use  file	word  as  standard  output.   If  the file exists, then output is
		     appended to it (by first seeking to the end-of-file); otherwise, the file is
		     created.

       <>word	     Open file word for reading and writing as standard output.

       <>;word	     The  same	as <>word except that if the command completes successfully, word
		     is truncated to the offset at command completion.	<>;word  cannot  be  used
		     with the exec(2).	built-in.

       <<[-]word     The  shell  input	is  read  up to a line that is the same as word after any
		     quoting has been removed, or to an end-of-file.  No parameter  substitution,
		     command  substitution,  arithmetic  substitution  or file name generation is
		     performed on word.  The resulting document, called a here-document,  becomes
		     the standard input.  If any character of word is quoted, then no interpreta-
		     tion is placed upon the characters of  the  document;  otherwise,	parameter
		     expansion,  command  substitution,  and arithmetic substitution occur, \new-
		     line is ignored, and \ must be used to quote the characters \, $, `.   If	-
		     is appended to <<, then all leading tabs are stripped from word and from the
		     document.	If # is appended to <<, then leading  spaces  and  tabs  will  be
		     stripped off the first line of the document and up to an equivalent indenta-
		     tion will be stripped from the remaining lines and from word.  A tab stop is
		     assumed  to  occur  at  every  8 columns for the purposes of determining the
		     indentation.

       <<<word	     A short form of here document in which word  becomes  the	contents  of  the
		     here-document  after  any	parameter  expansion,  command	substitution, and
		     arithmetic substitution occur.

       <&digit	     The standard input is duplicated from file descriptor  digit  (see  dup(2)).
		     Similarly for the standard output using >&digit.

       <&digit-      The  file	descriptor  given by digit is moved to standard input.	Similarly
		     for the standard output using >&digit-.

       <&-	     The standard input is closed.  Similarly for the standard output using >&-.

       <&p	     The input from the co-process is moved to standard input.

       >&p	     The output to the co-process is moved to standard output.

       <#((expr))    Evaluate arithmetic expression expr and position file descriptor  0  to  the
		     resulting value bytes from the start of the file.	The variables CUR and EOF
		     evaluate to the current offset  and  end-of-file  offset  respectively  when
		     evaluating expr.

       >#((offset))  The same as <# except applies to file descriptor 1.

       <#pattern     Seeks forward to the beginning of the next line containing pattern.

       <##pattern    The same as <# except that the portion of the file that is skipped is copied
		     to standard output.

       If one of the above is preceded by a digit, with  no  intervening  space,  then	the  file
       descriptor  number referred to is that specified by the digit (instead of the default 0 or
       1).  If one of the above, other than >&- and the ># and <# forms, is preceded by {varname}
       with  no  intervening  space,  then  a file descriptor number > 10 will be selected by the
       shell and stored in the variable varname.  If >&- or the any of the >#  and  <#	forms  is
       preceded  by  {varname} the value of varname defines the file descriptor to close or posi-
       tion.  For example:

	      ... 2>&1

       means file descriptor 2 is to be opened for writing as a duplicate of  file  descriptor	1
       and

	      exec {n}<file

       means open file named file for reading and store the file descriptor number in variable n.

       The  order  in  which redirections are specified is significant.  The shell evaluates each
       redirection in terms of the (file descriptor, file) association at the time of evaluation.
       For example:

	      ... 1>fname 2>&1

       first  associates file descriptor 1 with file fname.  It then associates file descriptor 2
       with the file associated with file descriptor 1 (i.e.  fname).  If the order  of  redirec-
       tions  were  reversed,  file  descriptor 2 would be associated with the terminal (assuming
       file descriptor 1 had been) and then file descriptor  1	would  be  associated  with  file
       fname.

       If  a  command  is  followed by & and job control is not active, then the default standard
       input for the command is the empty file /dev/null.  Otherwise,  the  environment  for  the
       execution  of a command contains the file descriptors of the invoking shell as modified by
       input/output specifications.

   Environment.
       The environment (see environ(7)) is a list of name-value pairs that is passed to  an  exe-
       cuted  program  in  the same way as a normal argument list.  The names must be identifiers
       and the values are character strings.  The shell interacts with the environment in several
       ways.  On invocation, the shell scans the environment and creates a variable for each name
       found, giving it the corresponding value and attributes and marking it  export.	 Executed
       commands  inherit  the environment.  If the user modifies the values of these variables or
       creates new ones, using the export or typeset -x commands, they become part of  the  envi-
       ronment.   The environment seen by any executed command is thus composed of any name-value
       pairs originally inherited by the shell, whose values  may  be  modified  by  the  current
       shell, plus any additions which must be noted in export or typeset -x commands.

       The  environment  for any simple-command or function may be augmented by prefixing it with
       one or more variable assignments.  A variable assignment argument is a word  of	the  form
       identifier=value.  Thus:

	      TERM=450 cmd args 		 and
	      (export TERM; TERM=450; cmd args)

       are  equivalent	(as  far  as  the  above execution of cmd is concerned except for special
       built-in commands listed below - those that are preceded with a dagger).

       If the obsolete -k option is set, all variable assignment  arguments  are  placed  in  the
       environment,  even if they occur after the command name.  The following first prints a=b c
       and then c:

	      echo a=b c
	      set -k
	      echo a=b c
       This feature is intended for use with scripts written for early versions of the shell  and
       its use in new scripts is strongly discouraged.	It is likely to disappear someday.

   Functions.
       For  historical reasons, there are two ways to define functions, the name() syntax and the
       function name syntax, described in the Commands section above.  Shell functions	are  read
       in  and stored internally.  Alias names are resolved when the function is read.	Functions
       are executed like commands with the arguments passed as positional parameters.  (See  Exe-
       cution below.)

       Functions  defined  by  the  function  name  syntax and called by name execute in the same
       process as the caller and share all files and present working directory with  the  caller.
       Traps  caught by the caller are reset to their default action inside the function.  A trap
       condition that is not caught or ignored by the function causes the function  to	terminate
       and  the condition to be passed on to the caller.  A trap on EXIT set inside a function is
       executed in the environment of the caller after the function completes.	Ordinarily, vari-
       ables  are shared between the calling program and the function.	However, the typeset spe-
       cial built-in command used within a function defines local variables whose scope  includes
       the  current  function.	 They  can  be passed to functions that they call in the variable
       assignment list that precedes the call or as arguments passed as name references.   Errors
       within functions return control to the caller.

       Functions defined with the name() syntax and functions defined with the function name syn-
       tax that are invoked with the .	special built-in are executed in the caller's environment
       and  share  all	variables and traps with the caller.  Errors within these function execu-
       tions cause the script that contains them to abort.

       The special built-in command return is used to return from function calls.

       Function names can be listed with the -f or +f option of the typeset special built-in com-
       mand.   The text of functions, when available, will also be listed with -f.  Functions can
       be undefined with the -f option of the unset special built-in command.

       Ordinarily, functions are unset when the shell executes a shell	script.   Functions  that
       need  to  be defined across separate invocations of the shell should be placed in a direc-
       tory and the FPATH variable should contain the name of this directory.  They may  also  be
       specified in the ENV file.

   Discipline Functions.
       Each  variable  can  have zero or more discipline functions associated with it.	The shell
       initially understands the discipline names get, set, append, and unset but  can	be  added
       when  defining  new types.  On most systems others can be added at run time via the C pro-
       gramming interface extension provided by the builtin built-in utility.  If the get  disci-
       pline  is defined for a variable, it is invoked whenever the given variable is referenced.
       If the variable .sh.value is assigned a value inside the discipline function,  the  refer-
       enced  variable will evaluate to this value instead.  If the set discipline is defined for
       a variable, it is invoked whenever the given variable is assigned a value.  If the  append
       discipline  is  defined	for a variable, it is invoked whenever a value is appended to the
       given variable.	The variable .sh.value is given the value of the variable before invoking
       the  discipline, and the variable will be assigned the value of .sh.value after the disci-
       pline completes.  If .sh.value  is  unset  inside  the  discipline,  then  that	value  is
       unchanged.   If the unset discipline is defined for a variable, it is invoked whenever the
       given variable is unset.  The variable will not be unset unless	it  is	unset  explicitly
       from within this discipline function.

       The  variable .sh.name contains the name of the variable for which the discipline function
       is called, .sh.subscript is the subscript of the variable, and .sh.value will contain  the
       value being assigned inside the set discipline function.  The variable _ is a reference to
       the variable including the subscript if any.  For the set discipline,  changing	.sh.value
       will  change  the value that gets assigned.  Finally, the expansion ${var.name}, when name
       is the name of a discipline, and there is no variable of this name, is equivalent  to  the
       command substitution ${ var.name;}.

   Name Spaces.
       Commands  and  functions that are executed as part of the list of a namespace command that
       modify variables or create new ones, create a new variable whose name is the name  of  the
       name  space  as	given by identifier preceded by ..  When a variable whose name is name is
       referenced, it is first	searched  for  using  .identifier.name.   Similarly,  a  function
       defined	by a command in the namespace list is created using the name space name  preceded
       by a ..

       When  the list of a namespace command contains a namespace command, the names of variables
       and  functions  that  are created consist of the variable or function name preceded by the
       list of identifiers each preceded by ..

       Outside of a name space, a variable or function created inside a name space can be  refer-
       enced by preceding it with the name space name.

       By default, variables staring with .sh are in the sh name space.

   Type Variables.
       Typed variables provide a way to create data structure and objects.  A type can be defined
       either by a shared library, by the enum built-in command described below, or by using  the
       new  -T	option	of the typeset built-in command.  With the -T option of typeset, the type
       name, specified as an option argument to -T, is set with a  compound  variable  assignment
       that  defines  the  type.   Function  definitions  can appear inside the compound variable
       assignment and these become discipline functions for this type and can be invoked or rede-
       fined by each instance of the type.  The function name create is treated specially.  It is
       invoked for each instance of the type that is created but is not inherited and  cannot  be
       redefined for each instance.

       When  a type is defined a special built-in command of that name is added.  These built-ins
       are declaration commands and follow the same expansion rules as all the	special  built-in
       commands  defined  below that are preceded by --.  These commands can subsequently be used
       inside further type definitions.  The man page for these  commands  can	be  generated  by
       using the --man option or any of the other -- options described with getopts.  The -r, -a,
       -A, -h, and -S options of typeset are permitted with each of these new built-ins.

       An instance of a type is created by invoking  the  type	name  followed	by  one  or  more
       instance names.	Each instance of the type is initialized with a copy of the sub-variables
       except for sub-variables that are defined with the -S option.  Variables defined with  the
       -S  are	shared	by  all instances of the type.	Each instance can change the value of any
       sub-variable and can also define new discipline functions  of  the  same  names	as  those
       defined	by  the  type definition as well as any standard discipline names.  No additional
       sub-variables can be defined for any instance.

       When defining a type, if the value of a sub-variable is not set and the	-r  attribute  is
       specified, it causes the sub-variable to be a required sub-variable.  Whenever an instance
       of a type is created, all required sub-variables must be specified.   These  sub-variables
       become readonly in each instance.

       When  unset  is invoked on a sub-variable within a type, and the -r attribute has not been
       specified for this field, the value is reset to the default  value  associative	with  the
       type.   Invoking  unset	on  a type instance not contained within another type deletes all
       sub-variables and the variable itself.

       A type definition can be derived from another type definition by defining the  first  sub-
       variable name as _ and defining its type as the base type.  Any remaining definitions will
       be additions and modifications that apply to the new type.  If the new type  name  is  the
       same  is  that  of  the base type, the type will be replaced and the original type will no
       longer be accessible.

       The typeset command with the -T and no option argument or operands will write all the type
       definitions  to	standard  output  in  a  form that that can be read in to create all they
       types.

   Jobs.
       If the monitor option of the set command is turned on, an interactive 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 asynchronously 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.

       This paragraph and the next require features that are not in all versions of UNIX and  may
       not  apply.  If you are running a job and wish to do something else you may hit the key ^Z
       (control-Z) which sends a STOP signal to the current job.  The shell  will  then  normally
       indicate  that the job has been `Stopped', and print another prompt.  You can then manipu-
       late the state of this job, putting it in the background with the bg command, or run  some
       other  commands	and then eventually bring the job back into the foreground with the fore-
       ground command fg.  A ^Z takes effect immediately and is like an interrupt in that pending
       output and unread input are discarded when it is typed.

       A  job being run in the background will stop if it tries to read from the terminal.  Back-
       ground jobs are normally allowed to produce output, but this can be disabled by giving the
       command 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.

       A job pool is a collection of jobs started with list & associated with a name.

       There are several ways to refer to jobs in the shell.  A job can be  referred  to  by  the
       process id of any process of the job or by one of the following:
       %number
	      The job with the given number.
       pool   All the jobs in the job pool named by pool.
       pool.number
	      The job number number in the job pool named by pool.
       %string
	      Any job whose command line begins with string.
       %?string
	      Any job whose command line contains string.
       %%     Current job.
       %+     Equivalent to %%.
       %-     Previous	job.   In  addition, unless noted otherwise, wherever a job can be speci-
	      fied, the name of a background job pool can be used to represent all  the  jobs  in
	      that pool.

       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  just
       before  it prints a prompt.  This is done so that it does not otherwise disturb your work.
       The notify option of the set command causes the shell to print these job  change  messages
       as soon as they occur.

       When  the  monitor  option is on, each background job that completes triggers any trap set
       for CHLD.

       When you try to leave the shell while jobs are running or stopped, you will be warned that
       `You  have stopped(running) jobs.'  You may use the jobs command to see what they are.  If
       you immediately try to exit again, the shell will not warn you  a  second  time,  and  the
       stopped jobs will be terminated.  When a login shell receives a HUP signal, it sends a HUP
       signal to each job that has not been disowned with the disown built-in  command	described
       below.

   Signals.
       The  INT and QUIT signals for an invoked command are ignored if the command is followed by
       & and the monitor option is not active.	Otherwise, signals have the values  inherited  by
       the shell from its parent (but see also the trap built-in command below).

   Execution.
       Each time a command is read, the above substitutions are carried out.  If the command name
       matches one of the Special Built-in Commands listed below, it is executed within the  cur-
       rent shell process.  Next, the command name is checked to see if it matches a user defined
       function.  If it does, the positional parameters are saved and then reset to the arguments
       of the function call.  A function is also executed in the current shell process.  When the
       function completes or issues a return, the positional parameter	list  is  restored.   For
       functions  defined with the function name syntax, any trap set on EXIT within the function
       is executed.  The exit value of a function is the value of the last command executed.   If
       a command name is not a special built-in command or a user defined function, but it is one
       of the built-in commands listed below, it is executed in the current shell process.

       The shell variables PATH followed by the variable FPATH defines the list of directories to
       search  for  the  command name.	Alternative directory names are separated by a colon (:).
       The default path is equal to getconf PATH output.  The current directory can be	specified
       by  two	or  more adjacent colons, or by a colon at the beginning or end of the path list.
       If the command name contains a /, then the search  path	is  not  used.	 Otherwise,  each
       directory  in  the  list of directories defined by PATH and FPATH is checked in order.  If
       the directory being searched is contained in FPATH and contains a file whose name  matches
       the command being searched, then this file is loaded into the current shell environment as
       if it were the argument to the . command except that only preset aliases are expanded, and
       a function of the given name is executed as described above.

       If  this  directory is not in FPATH the shell first determines whether there is a built-in
       version of a command corresponding to a given pathname and if so it is invoked in the cur-
       rent  process.	If no built-in is found, the shell checks for a file named .paths in this
       directory.  If found and there is a line of the form FPATH=path where path names an exist-
       ing  directory  then that directory is searched after immediately after the current direc-
       tory as if it were found in the FPATH variable.	If path does not  begin  with  /,  it  is
       checked for relative to the directory being searched.

       The  .paths  file is then checked  for a line of the form PLUGIN_LIB=libname [ : libname ]
       ... .  Each library named by libname will be searched for as if it were an option argument
       to  builtin  -f, and if it contains a built-in of the specified name this will be executed
       instead of a command by this name.  Any built-in loaded from a library found this way will
       be associated with the directory containing the .paths file so it will only execute if not
       found in an earlier directory.

       Finally, the directory will be checked for a file of the given name.  If the file has exe-
       cute permission but is not an a.out file, it is assumed to be a file containing shell com-
       mands.  A separate shell is spawned to read it.	All non-exported variables are removed in
       this  case.   If  the  shell  command  file doesn't have read permission, or if the setuid
       and/or setgid bits are set on the file, then the shell executes an agent whose job  it  is
       to set up the permissions and execute the shell with the shell command file passed down as
       an open file.  If the .paths contains a line of the form name=value in the first or second
       line, then the environment variable name is modified by prepending the directory specified
       by value to the directory list.	If value is not an absolute directory, then it	specifies
       a  directory  relative to the directory that the executable was found.  If the environment
       variable name does not already exist it will be added to  the  environment  list  for  the
       specified  command.   A	parenthesized command is executed in a sub-shell without removing
       non-exported variables.

   Command Re-entry.
       The text of the last HISTSIZE (default 512) commands entered from  a  terminal  device  is
       saved  in  a history file.  The file $HOME/.sh_history is used if the HISTFILE variable is
       not set or if the file it names is not writable.  A shell can access the commands  of  all
       interactive  shells  which use the same named HISTFILE.	The built-in command hist is used
       to list or edit a portion of this file.	The portion of the file to be  edited  or  listed
       can  be	selected by number or by giving the first character or characters of the command.
       A single command or range of commands can be specified.	If you do not specify  an  editor
       program as an argument to hist then the value of the variable HISTEDIT is used.	If HISTE-
       DIT is unset, the obsolete variable FCEDIT is  used.   If  FCEDIT  is  not  defined,  then
       /bin/ed is used.  The edited command(s) is printed and re-executed upon leaving the editor
       unless you quit without writing.  The -s option (and in obsolete versions, the editor name
       -)  is  used to skip the editing phase and to re-execute the command.  In this case a sub-
       stitution parameter of the form old=new can be used to modify the  command  before  execu-
       tion.   For  example,  with  the  preset alias r, which is aliased to 'hist -s', typing `r
       bad=good c' will re-execute the most recent  command  which  starts  with  the  letter  c,
       replacing the first occurrence of the string bad with the string good.

   In-line Editing Options.
       Normally,  each	command line entered from a terminal device is simply typed followed by a
       new-line (`RETURN' or `LINE FEED').  If either the emacs, gmacs, or vi option  is  active,
       the  user  can  edit the command line.  To be in either of these edit modes set the corre-
       sponding option.  An editing option is automatically selected each time the VISUAL or EDI-
       TOR variable is assigned a value ending in either of these option names.

       The  editing  features require that the user's terminal accept `RETURN' as carriage return
       without line feed and that a space (` ') must  overwrite  the  current  character  on  the
       screen.

       Unless the multiline option is on, the editing modes implement a concept where the user is
       looking through a window at the current line.  The window width is the value of COLUMNS if
       it  is  defined, otherwise 80.  If the window width is too small to display the prompt and
       leave at least 8 columns to enter input, the prompt is truncated from the  left.   If  the
       line is longer than the window width minus two, a mark is displayed at the end of the win-
       dow to notify the user.	As the cursor moves and reaches the window boundaries the  window
       will  be  centered  about  the  cursor.	The mark is a > (<, *) if the line extends on the
       right (left, both) side(s) of the window.

       The search commands in each edit mode provide access to the history  file.   Only  strings
       are matched, not patterns, although a leading ^ in the string restricts the match to begin
       at the first character in the line.

       Each of the edit modes has an operation to list the files or commands that  match  a  par-
       tially  entered word.  When applied to the first word on the line, or the first word after
       a ;, |, &, or (, and the word does not begin with ~ or contain a /, the list  of  aliases,
       functions,  and executable commands defined by the PATH variable that could match the par-
       tial word is displayed.	Otherwise, the list of files that match the given  word  is  dis-
       played.	If the partially entered word does not contain any file expansion characters, a *
       is appended before generating these lists.  After displaying the generated list, the input
       line  is redrawn.  These operations are called command name listing and file name listing,
       respectively.  There are additional operations, referred to as command name completion and
       file name completion, which compute the list of matching commands or files, but instead of
       printing the list, replace the current word with a complete or partial  match.	For  file
       name  completion, if the match is unique, a / is appended if the file is a directory and a
       space is appended if the file is not a directory.  Otherwise, the  longest  common  prefix
       for  all the matching files replaces the word.  For command name completion, only the por-
       tion of the file names after the last / are used to find the longest command  prefix.   If
       only  a	single	name matches this prefix, then the word is replaced with the command name
       followed by a space.  When using a tab for completion that does not yield a unique  match,
       a subsequent tab will provide a numbered list of matching alternatives.	A specific selec-
       tion can be made by entering the selection number followed by a tab.

   Key Bindings.
       The KEYBD trap can be used to intercept keys as they are typed and change  the  characters
       that  are  actually  seen  by  the  shell.  This trap is executed after each character (or
       sequence of characters when the first character is ESC) is entered while  reading  from	a
       terminal.  The variable .sh.edchar contains the character or character sequence which gen-
       erated the trap.  Changing the value of .sh.edchar in the trap action causes the shell  to
       behave as if the new value were entered from the keyboard rather than the original value.

       The  variable .sh.edcol is set to the input column number of the cursor at the time of the
       input.  The variable .sh.edmode is set to ESC when in vi insert mode (see  below)  and  is
       null  otherwise.   By prepending ${.sh.editmode} to a value assigned to .sh.edchar it will
       cause the shell to change to control mode if it is not already in this mode.

       This trap is not invoked for characters entered as arguments  to  editing  directives,  or
       while reading input for a character search.

   Emacs Editing Mode.
       This  mode  is  entered by enabling either the emacs or gmacs option.  The only difference
       between these two modes is the way they handle ^T.  To edit, the user moves the cursor  to
       the  point  needing  correction and then inserts or deletes characters or words as needed.
       All the editing commands are control characters or escape  sequences.   The  notation  for
       control	characters  is caret (^) followed by the character.  For example, ^F is the nota-
       tion for control F.  This is entered by depressing `f' while holding down the `CTRL' (con-
       trol)  key.   The  `SHIFT'  key	is  not  depressed.   (The notation ^?	indicates the DEL
       (delete) key.)

       The notation for escape sequences is M- followed by a character.  For example,  M-f  (pro-
       nounced	Meta  f) is entered by depressing ESC (ascii 033) followed by `f'.  (M-F would be
       the notation for ESC followed by `SHIFT' (capital) `F'.)

       All edit commands operate from any place on the line (not just at the beginning).  Neither
       the `RETURN' nor the `LINE FEED' key is entered after edit commands except when noted.

       ^F	 Move cursor forward (right) one character.
       M-[C	 Move cursor forward (right) one character.
       M-f	 Move cursor forward one word.	(The emacs editor's idea of a word is a string of
		 characters consisting of only letters, digits and underscores.)
       ^B	 Move cursor backward (left) one character.
       M-[D	 Move cursor backward (left) one character.
       M-b	 Move cursor backward one word.
       ^A	 Move cursor to start of line.
       M-[H	 Move cursor to start of line.
       ^E	 Move cursor to end of line.
       M-[Y	 Move cursor to end of line.
       ^]char	 Move cursor forward to character char on current line.
       M-^]char  Move cursor backward to character char on current line.
       ^X^X	 Interchange the cursor and mark.
       erase	 (User defined erase character as defined by the stty(1) command, usually  ^H  or
		 #.)  Delete previous character.
       lnext	 (User defined literal next character as defined by the stty(1) command, or ^V if
		 not defined.)	Removes the next character's editing features (if any).
       ^D	 Delete current character.
       M-d	 Delete current word.
       M-^H	 (Meta-backspace) Delete previous word.
       M-h	 Delete previous word.
       M-^?	 (Meta-DEL) Delete previous word (if your interrupt character is  ^?   (DEL,  the
		 default) then this command will not work).
       ^T	 Transpose  current  character	with previous character and advance the cursor in
		 emacs mode.  Transpose two previous characters in gmacs mode.
       ^C	 Capitalize current character.
       M-c	 Capitalize current word.
       M-l	 Change the current word to lower case.
       ^K	 Delete from the cursor to the end of the  line.   If  preceded  by  a	numerical
		 parameter whose value is less than the current cursor position, then delete from
		 given position up to the cursor.  If preceded by  a  numerical  parameter  whose
		 value is greater than the current cursor position, then delete from cursor up to
		 given cursor position.
       ^W	 Kill from the cursor to the mark.
       M-p	 Push the region from the cursor to the mark on the stack.
       kill	 (User defined kill character as defined by the stty command, usually ^G  or  @.)
		 Kill the entire current line.	If two kill characters are entered in succession,
		 all kill characters from then on cause a line feed (useful when using paper ter-
		 minals).
       ^Y	 Restore last item removed from line. (Yank item back to the line.)
       ^L	 Line feed and print current line.
       M-^L	 Clear the screen.
       ^@	 (Null character) Set mark.
       M-space	 (Meta space) Set mark.
       ^J	 (New line) Execute the current line.
       ^M	 (Return) Execute the current line.
       eof	 End-of-file  character,  normally ^D, is processed as an End-of-file only if the
		 current line is null.
       ^P	 Fetch previous command.  Each time ^P is entered the previous	command  back  in
		 time  is  accessed.   Moves back one line when not on the first line of a multi-
		 line command.
       M-[A	 If the cursor is at the end of the line, it is equivalent to ^R with string  set
		 to the contents of the current line.  Otherwise, it is equivalent to ^P.
       M-<	 Fetch the least recent (oldest) history line.
       M->	 Fetch the most recent (youngest) history line.
       ^N	 Fetch	next command line.  Each time ^N is entered the next command line forward
		 in time is accessed.
       M-[B	 Equivalent to ^N.
       ^Rstring  Reverse search history for a previous command	line  containing  string.   If	a
		 parameter  of	zero  is given, the search is forward.	String is terminated by a
		 `RETURN' or `NEW LINE'.  If string is preceded by a ^,  the  matched  line  must
		 begin	with string.  If string is omitted, then the next command line containing
		 the most recent string is accessed.  In this case a parameter of  zero  reverses
		 the direction of the search.
       ^O	 Operate  -  Execute the current line and fetch the next line relative to current
		 line from the history file.
       M-digits  (Escape) Define numeric parameter, the digits are taken as a  parameter  to  the
		 next  command.   The commands that accept a parameter are ^F, ^B, erase, ^C, ^D,
		 ^K, ^R, ^P, ^N, ^], M-., M-^], M-_, M-=, M-b, M-c, M-d, M-f, M-h, M-l and M-^H.
       M-letter  Soft-key - Your alias list is searched for an alias by the name _letter  and  if
		 an alias of this name is defined, its value will be inserted on the input queue.
		 The letter must not be one of the above meta-functions.
       M-[letter Soft-key - Your alias list is searched for an alias by the name __letter and  if
		 an alias of this name is defined, its value will be inserted on the input queue.
		 This can be used to program function keys on many terminals.
       M-.	 The last word of the previous command is inserted on the line.  If preceded by a
		 numeric  parameter,  the value of this parameter determines which word to insert
		 rather than the last word.
       M-_	 Same as M-..
       M-*	 Attempt file name generation on the current word.  An asterisk  is  appended  if
		 the word doesn't match any file or contain any special pattern characters.
       M-ESC	 Command or file name completion as described above.
       ^I tab	 Attempts  command or file name completion as described above.	If a partial com-
		 pletion occurs, repeating this will behave as if M-= were entered.  If no  match
		 is found or entered after space, a tab is inserted.
       M-=	 If  not  preceded by a numeric parameter, it generates the list of matching com-
		 mands or file names as described above.  Otherwise, the word under the cursor is
		 replaced  by  the  item corresponding to the value of the numeric parameter from
		 the most recently generated command or file list.  If the cursor  is  not  on	a
		 word, it is inserted instead.
       ^U	 Multiply parameter of next command by 4.
       \	 Escape next character.  Editing characters, the user's erase, kill and interrupt
		 (normally ^?)	characters may be entered in a command line or in a search string
		 if  preceded  by  a  \.  The \ removes the next character's editing features (if
		 any).
       M-^V	 Display version of the shell.
       M-#	 If the line does not begin with a #, a # is inserted at  the  beginning  of  the
		 line and after each new-line, and the line is entered.  This causes a comment to
		 be inserted in the history file.  If the line begins with a #, the # is  deleted
		 and one # after each new-line is also deleted.

   Vi Editing Mode.
       There  are  two	typing	modes.	 Initially, when you enter a command you are in the input
       mode.  To edit, the user enters control mode by typing ESC (033) and moves the  cursor  to
       the  point  needing  correction and then inserts or deletes characters or words as needed.
       Most control commands accept an optional repeat count prior to the command.

       When in vi mode on most systems, canonical processing is initially enabled and the command
       will  be  echoed  again	if  the speed is 1200 baud or greater and it contains any control
       characters or less than one second has elapsed since the  prompt  was  printed.	 The  ESC
       character  terminates  canonical  processing for the remainder of the command and the user
       can then modify the command line.  This scheme has the advantages of canonical  processing
       with the type-ahead echoing of raw mode.

       If  the	option viraw is also set, the terminal will always have canonical processing dis-
       abled.  This mode is implicit for systems that do not support two alternate  end  of  line
       delimiters, and may be helpful for certain terminals.

	Input Edit Commands
	      By default the editor is in input mode.
	      erase	(User  defined erase character as defined by the stty command, usually ^H
			or #.)	Delete previous character.
	      ^W	Delete the previous blank separated word.   On	some  systems  the  viraw
			option may be required for this to work.
	      eof	As  the  first character of the line causes the shell to terminate unless
			the ignoreeof option is set.  Otherwise this character is ignored.
	      lnext	(User defined literal next character as defined by the stty(1) or  ^V  if
			not  defined.)	 Removes  the next character's editing features (if any).
			On some systems the viraw option may be required for this to work.
	      \ 	Escape the next erase or kill character.
	      ^I tab	Attempts command or file name completion as described above  and  returns
			to  input  mode.   If  a  partial  completion occurs, repeating this will
			behave as if = were entered from control mode.	If no match is	found  or
			entered after space, a tab is inserted.
	Motion Edit Commands
	      These commands will move the cursor.
	      [count]l	Cursor forward (right) one character.
	      [count][C Cursor forward (right) one character.
	      [count]w	Cursor forward one alpha-numeric word.
	      [count]W	Cursor to the beginning of the next word that follows a blank.
	      [count]e	Cursor to end of word.
	      [count]E	Cursor to end of the current blank delimited word.
	      [count]h	Cursor backward (left) one character.
	      [count][D Cursor backward (left) one character.
	      [count]b	Cursor backward one word.
	      [count]B	Cursor to preceding blank separated word.
	      [count]|	Cursor to column count.
	      [count]fc Find the next character c in the current line.
	      [count]Fc Find the previous character c in the current line.
	      [count]tc Equivalent to f followed by h.
	      [count]Tc Equivalent to F followed by l.
	      [count];	Repeats  count times, the last single character find command, f, F, t, or
			T.
	      [count],	Reverses the last single character find command count times.
	      0 	Cursor to start of line.
	      ^ 	Cursor to start of line.
	      [H	Cursor to first non-blank character in line.
	      $ 	Cursor to end of line.
	      [Y	Cursor to end of line.
	      % 	Moves to balancing (, ), {, }, [, or ].  If cursor is not on one  of  the
			above  characters,  the  remainder  of the line is searched for the first
			occurrence of one of the above characters first.
	Search Edit Commands
	      These commands access your command history.
	      [count]k	Fetch previous command.  Each time k is entered the previous command back
			in time is accessed.
	      [count]-	Equivalent to k.
	      [count][A If cursor is at the end of the line it is equivalent to / with string^set
			to the contents of the current line.  Otherwise, it is equivalent to k.
	      [count]j	Fetch next command.  Each time j is entered the next command  forward  in
			time is accessed.
	      [count]+	Equivalent to j.
	      [count][B Equivalent to j.
	      [count]G	The  command  number  count  is fetched.  The default is the least recent
			history command.
	      /string	Search backward through history for a previous command containing string.
			String	is terminated by a `RETURN' or `NEW LINE'.  If string is preceded
			by a ^, the matched line must begin with string.  If string is null,  the
			previous string will be used.
	      ?string	Same as / except that search will be in the forward direction.
	      n 	Search for next match of the last pattern to / or ?  commands.
	      N 	Search	for  next  match  of  the  last pattern to / or ?, but in reverse
			direction.
	Text Modification Edit Commands
	      These commands will modify the line.
	      a 	Enter input mode and enter text after the current character.
	      A 	Append text to the end of the line.  Equivalent to $a.
	      [count]cmotion
	      c[count]motion
			Delete current character through the character that motion would move the
			cursor	to and enter input mode.  If motion is c, the entire line will be
			deleted and input mode entered.
	      C 	Delete the current character through the end  of  line	and  enter  input
			mode.  Equivalent to c$.
	      S 	Equivalent to cc.
	      [count]s	Replace characters under the cursor in input mode.
	      D 	Delete the current character through the end of line.  Equivalent to d$.
	      [count]dmotion
	      d[count]motion
			Delete current character through the character that motion would move to.
			If motion is d , the entire line will be deleted.
	      i 	Enter input mode and insert text before the current character.
	      I 	Insert text before the beginning of the line.  Equivalent to 0i.
	      [count]P	Place the previous text modification before the cursor.
	      [count]p	Place the previous text modification after the cursor.
	      R 	Enter input mode and replace characters on the screen with characters you
			type overlay fashion.
	      [count]rc Replace  the  count  character(s) starting at the current cursor position
			with c, and advance the cursor.
	      [count]x	Delete current character.
	      [count]X	Delete preceding character.
	      [count].	Repeat the previous text modification command.
	      [count]~	Invert the case of the count character(s) starting at the current  cursor
			position and advance the cursor.
	      [count]_	Causes	the  count  word of the previous command to be appended and input
			mode entered.  The last word is used if count is omitted.
	      * 	Causes an * to be appended to the current word and file  name  generation
			attempted.  If no match is found, it rings the bell.  Otherwise, the word
			is replaced by the matching pattern and input mode is entered.
	      \ 	Command or file name completion as described above.
	Other Edit Commands
	      Miscellaneous commands.
	      [count]ymotion
	      y[count]motion
			Yank current character through character that motion would move the  cur-
			sor  to  and  puts  them into the delete buffer.  The text and cursor are
			unchanged.
	      yy	Yanks the entire line.
	      Y 	Yanks from current position to end of line.  Equivalent to y$.
	      u 	Undo the last text modifying command.
	      U 	Undo all the text modifying commands performed on the line.
	      [count]v	Returns the command hist -e ${VISUAL:-${EDITOR:-vi}} count in  the  input
			buffer.  If count is omitted, then the current line is used.
	      ^L	Line feed and print current line.  Has effect only in control mode.
	      ^J	(New line) Execute the current line, regardless of mode.
	      ^M	(Return) Execute the current line, regardless of mode.
	      # 	If  the  first character of the command is a #, then this command deletes
			this # and each # that follows a  newline.   Otherwise,  sends	the  line
			after  inserting  a  #	in front of each line in the command.  Useful for
			causing the current line to be inserted in the history as a  comment  and
			uncommenting previously commented commands in the history file.
	      [count]=	If  count is not specified, it generates the list of matching commands or
			file names as described above.	Otherwise, the word under the the  cursor
			is replaced by the count item from the most recently generated command or
			file list.  If the cursor is not on a word, it is inserted instead.
	      @letter	Your alias list is searched for an alias by the name _letter  and  if  an
			alias  of  this  name is defined, its value will be inserted on the input
			queue for processing.
	      ^V	Display version of the shell.

   Built-in Commands.
       The following simple-commands are executed in the shell process.  Input/Output redirection
       is  permitted.  Unless otherwise indicated, the output is written on file descriptor 1 and
       the exit status, when there is no syntax error, is zero.  Except for :, true, false, echo,
       newgrp,	and login, all built-in commands accept -- to indicate end of options.	They also
       interpret the option --man as a request to display the man page onto standard error and -?
       as  a help request which prints a usage message on standard error.  Commands that are pre-
       ceded by one or two - symbols are special built-in commands and are treated  specially  in
       the following ways:
       1.     Variable	assignment  lists preceding the command remain in effect when the command
	      completes.
       2.     I/O redirections are processed after variable assignments.
       3.     Errors cause a script that contains them to abort.
       4.     They are not valid function names.
       5.     Words following a command preceded by -- that are  in  the  format  of  a  variable
	      assignment  are  expanded with the same rules as a variable assignment.  This means
	      that tilde substitution is performed after the = sign and field splitting and  file
	      name generation are not performed.  These are called declaration built-ins.

       - : [ arg ... ]
	      The command only expands parameters.

       - . name [ arg ... ]
	      If  name	is  a  function  defined with the function name reserved word syntax, the
	      function is executed in the current environment (as if it had been defined with the
	      name()  syntax.)	 Otherwise  if	name  refers  to  a file, the file is read in its
	      entirety and the commands are executed  in  the  current	shell  environment.   The
	      search  path  specified  by PATH is used to find the directory containing the file.
	      If any arguments arg are given, they become the positional  parameters  while  pro-
	      cessing  the  .	command  and the original positional parameters are restored upon
	      completion.  Otherwise the positional parameters are unchanged.  The exit status is
	      the exit status of the last command executed.

       -- alias [ -ptx ]  [ name[ =value  ] ] ...
	      alias  with no arguments prints the list of aliases in the form name=value on stan-
	      dard output.  The -p option causes the word alias to be inserted before  each  one.
	      When one or more arguments are given, an alias is defined for each name whose value
	      is given.  A trailing space in value causes the next word to be checked  for  alias
	      substitution.  The obsolete -t option is used to set and list tracked aliases.  The
	      value of a tracked alias is the full pathname corresponding to the given name.  The
	      value  becomes  undefined  when  the  value  of PATH is reset but the alias remains
	      tracked.	Without the -t option, for each name in the argument list  for	which  no
	      value is given, the name and value of the alias is printed.  The obsolete -x option
	      has no effect.  The exit status is non-zero if a name is given, but no  value,  and
	      no alias has been defined for the name.

       bg [ job... ]
	      This  command is only on systems that support job control.  Puts each specified job
	      into the background.  The current job is put in the background if job is not speci-
	      fied.  See Jobs for a description of the format of job.

       - break [ n ]
	      Exit  from the enclosing for, while, until, or select loop, if any.  If n is speci-
	      fied, then break n levels.

       builtin [ -ds ] [ -f file ] [ name ... ]
	      If name is not specified, and no -f option is specified, the built-ins are  printed
	      on  standard  output.  The -s option prints only the special built-ins.  Otherwise,
	      each name represents the pathname whose basename is the name of the built-in.   The
	      entry  point  function name is determined by prepending b_ to the built-in name.	A
	      built-in specified by a pathname will only be executed when that pathname would  be
	      found  during  the path search.  Built-ins found in libraries loaded via the .paths
	      file will be associate with the pathname of the  directory  containing  the  .paths
	      file.

       The  ISO  C/C++	prototype  is  b_mycommand(int argc, char *argv[], void *context) for the
       builtin command mycommand where argv is array an  of  argc  elements  and  context  is  an
       optional pointer to a Shell_t structure as described in <ast/shell.h>.
       Special built-ins cannot be bound to a pathname or deleted.  The -d option deletes each of
       the given built-ins.  On systems that support dynamic  loading,	the  -f  option  names	a
       shared  library	containing the code for built-ins.  The shared library prefix and/or suf-
       fix, which depend on the system, can be omitted.  Once a library is  loaded,  its  symbols
       become  available for subsequent invocations of builtin.  Multiple libraries can be speci-
       fied with separate invocations of the builtin command.	Libraries  are	searched  in  the
       reverse order in which they are specified.  When a library is loaded, it looks for a func-
       tion in the library whose name is lib_init() and invokes this function with an argument of
       0.

       cd [ -LP ] [ arg ]
       cd [ -LP ] old new
	      This  command can be in either of two forms.  In the first form it changes the cur-
	      rent directory to arg.  If arg is - the directory is changed to the previous direc-
	      tory.   The shell variable HOME is the default arg.  The variable PWD is set to the
	      current directory.  The shell variable CDPATH  defines  the  search  path  for  the
	      directory  containing  arg.   Alternative  directory names are separated by a colon
	      (:).  The default path is <null> (specifying the current directory).  Note that the
	      current  directory  is  specified by a null path name, which can appear immediately
	      after the equal sign or between the colon delimiters  anywhere  else  in	the  path
	      list.   If  arg  begins with a / then the search path is not used.  Otherwise, each
	      directory in the path is searched for arg.
	      The second form of cd substitutes the string new for the string old in the  current
	      directory name, PWD, and tries to change to this new directory.
	      By  default,  symbolic  link names are treated literally when finding the directory
	      name.  This is equivalent to the -L option.  The -P option causes symbolic links to
	      be  resolved  when determining the directory.  The last instance of -L or -P on the
	      command line determines which method is used.
	      The cd command may not be executed by rksh.  rksh93.

       command [ -pvxV ] name [ arg ... ]
	      Without the -v or -V options, command executes name with	the  arguments	given  by
	      arg.   The  -p  option  causes  a  default  path to be searched rather than the one
	      defined by the value of PATH.  Functions will not  be  searched  for  when  finding
	      name.  In addition, if name refers to a special built-in, none of the special prop-
	      erties associated with the leading daggers will be honored.  (For example, the pre-
	      defined  alias  redirect='command  exec' prevents a script from terminating when an
	      invalid redirection is given.)  With the -x  option,  if	command  execution  would
	      result  in  a  failure because there are too many arguments, errno E2BIG, the shell
	      will invoke command name multiple times with a subset  of  the  arguments  on  each
	      invocation.   Arguments that occur prior to the first word that expands to multiple
	      arguments and after the last word that expands to multiple arguments will be passed
	      on  each	invocation.   The exit status will be the maximum invocation exit status.
	      With the -v option, command is equivalent to the built-in whence command	described
	      below.  The -V option causes command to act like whence -v.

       - continue [ n ]
	      Resume the next iteration of the enclosing for, while, until, or select loop.  If n
	      is specified, then resume at the n-th enclosing loop.

       disown [ job... ]
	      Causes the shell not to send a HUP signal to each given job, or all active jobs  if
	      job is omitted, when a login shell terminates.

       echo [ arg ... ]
	      When  the first arg does not begin with a -, and none of the arguments contain a \,
	      then echo prints each of its arguments separated by a space  and	terminated  by	a
	      new-line.   Otherwise, the behavior of echo is system dependent and print or printf
	      described below should be used.  See echo(1) for usage and description.

       -- enum [ -i  ] type[=(value ...) ]
	      Creates a declaration command named type that is an integer type that allows one of
	      the  specified  values as enumeration names.  If =(value ...) is omitted, then type
	      must be an indexed array variable with at least two elements  and  the  values  are
	      taken  from  this  array variable.  If -i is specified the values are case insensi-
	      tive.

       - eval [ arg ... ]
	      The arguments are read as input to the shell and the resulting command(s) executed.

       - exec [ -c ] [ -a name ] [ arg ... ]
	      If arg is given, the command specified by the arguments is  executed  in	place  of
	      this shell without creating a new process.  The -c option causes the environment to
	      be cleared before applying variable assignments associated with  the  exec  invoca-
	      tion.   The  -a option causes name rather than the first arg, to become argv[0] for
	      the new process.	Input/output arguments may appear and affect the current process.
	      If  arg  is  not given, the effect of this command is to modify file descriptors as
	      prescribed by the input/output redirection list.	In this case, any file descriptor
	      numbers greater than 2 that are opened with this mechanism are closed when invoking
	      another program.

       - exit [ n ]
	      Causes the shell to exit with the exit status specified by n.  The  value  will  be
	      the  least  significant  8 bits of the specified status.	If n is omitted, then the
	      exit status is that of the last command executed.  An end-of-file will  also  cause
	      the shell to exit except for a shell which has the ignoreeof option (see set below)
	      turned on.

       -- export [ -p ] [ name[=value] ] ...
	      If name is not given, the names  and  values  of	each  variable	with  the  export
	      attribute are printed with the values quoted in a manner that allows them to be re-
	      input.  The export command is the same as typeset -x except that if you use  export
	      within  a  function,  no	local variable is created.  The -p option causes the word
	      export to be inserted before each one.  Otherwise, the given names are  marked  for
	      automatic export to the environment of subsequently-executed commands.

       false  Does nothing, and exits 1. Used with until for infinite loops.

       fg [ job... ]
	      This  command  is  only on systems that support job control.  Each job specified is
	      brought to the foreground and waited for in the specified  order.   Otherwise,  the
	      current job is brought into the foreground.  See Jobs for a description of the for-
	      mat of job.

       getconf [ name [ pathname ] ]
	      Prints the current value of the configuration parameter given by name.  The config-
	      uration parameters are defined by the IEEE POSIX 1003.1 and IEEE POSIX 1003.2 stan-
	      dards.  (See pathconf(2) and sysconf(2).)  The pathname argument	is  required  for
	      parameters whose value depends on the location in the file system.  If no arguments
	      are given, getconf prints the names and values of the current configuration parame-
	      ters.  The pathname / is used for each of the parameters that requires pathname.

       getopts [  -a name ] optstring vname [ arg ... ]
	      Checks  arg  for	legal  options.  If arg is omitted, the positional parameters are
	      used.  An option argument begins with a + or a -.  An option not beginning  with	+
	      or - or the argument -- ends the options.  Options beginning with + are only recog-
	      nized when optstring begins with a +.  optstring contains the letters that  getopts
	      recognizes.   If	a  letter  is followed by a :, that option is expected to have an
	      argument.  The options can be separated from the argument by blanks.  The option -?
	      causes  getopts to generate a usage message on standard error.  The -a argument can
	      be used to specify the name to use for the usage message, which defaults to $0.
	      getopts places the next option letter it finds inside variable vname each  time  it
	      is invoked.  The option letter will be prepended with a + when arg begins with a +.
	      The index of the next arg is stored in OPTIND.  The option argument, if  any,  gets
	      stored in OPTARG.
	      A leading : in optstring causes getopts to store the letter of an invalid option in
	      OPTARG, and to set vname to ?  for an unknown option  and  to  :	when  a  required
	      option  argument is missing.  Otherwise, getopts prints an error message.  The exit
	      status is non-zero when there are no more options.
	      There is no way to specify any of the options :, +, -, ?, [, and ].  The	option	#
	      can only be specified as the first option.

       hist [ -e ename	] [ -nlr ] [ first [ last ] ]
       hist -s	[ old=new ] [ command ]
	      In the first form, a range of commands from first to last is selected from the last
	      HISTSIZE commands that were typed at the terminal.  The arguments  first	and  last
	      may  be  specified as a number or as a string.  A string is used to locate the most
	      recent command starting with the given string.  A negative number  is  used  as  an
	      offset  to  the current command number.  If the -l option is selected, the commands
	      are listed on standard output.  Otherwise, the editor program ename is invoked on a
	      file  containing these keyboard commands.  If ename is not supplied, then the value
	      of the variable HISTEDIT is used.  If HISTEDIT is not  set,  then  FCEDIT  (default
	      /bin/ed) is used as the editor.  When editing is complete, the edited command(s) is
	      executed if the changes have been saved.	If last is not specified, then it will be
	      set  to  first.  If first is not specified, the default is the previous command for
	      editing and -16 for listing.  The option -r reverses the order of the commands  and
	      the option -n suppresses command numbers when listing.  In the second form, command
	      is interpreted as first described above and defaults to the last command	executed.
	      The  resulting  command is executed after the optional substitution old=new is per-
	      formed.

       jobs [ -lnp ] [ job ... ]
	      Lists information about each given job; or all active jobs if job is omitted.   The
	      -l  option  lists process ids in addition to the normal information.  The -n option
	      only displays jobs that have stopped or exited since last notified.  The -p  option
	      causes only the process group to be listed.  See Jobs for a description of the for-
	      mat of job.

       kill [ -s signame ] job ...
       kill [ -n signum ] job ...
       kill -Ll [ sig ... ]
	      Sends either the TERM (terminate) signal or the specified signal to  the	specified
	      jobs  or	processes.   Signals  are either given by number with the -n option or by
	      name with the -s option (as given in <signal.h>, stripped  of  the  prefix  ``SIG''
	      with  the  exception that SIGCLD is named CHLD).	For backward compatibility, the n
	      and s can be omitted and the number or name placed immediately after the -.  If the
	      signal being sent is TERM (terminate) or HUP (hangup), then the job or process will
	      be sent a CONT (continue) signal if it is stopped.  The argument	job  can  be  the
	      process  id  of a process that is not a member of one of the active jobs.  See Jobs
	      for a description of the format of job.  In the third form, kill -l, or kill -L, if
	      sig  is  not  specified,	the signal names are listed.  The -l option list only the
	      signal names.  -L options lists each signal name and corresponding number.   Other-
	      wise,  for each sig that is a name, the corresponding signal number is listed.  For
	      each sig that is a number, the signal name corresponding to the least significant 8
	      bits of sig is listed.

       let arg ...
	      Each  arg is a separate arithmetic expression to be evaluated.  let only recognizes
	      octal constants starting with 0 when the set option letoctal is on.  See Arithmetic
	      Evaluation above, for a description of arithmetic expression evaluation.
	      The  exit status is 0 if the value of the last expression is non-zero, and 1 other-
	      wise.

       - newgrp [ arg ... ]
	      Equivalent to exec /bin/newgrp arg ....

       print [ -CRenprsv ] [ -u unit] [ -f format ] [ arg ... ]
	      With no options or with option - or --, each arg is  printed  on	standard  output.
	      The  -f  option causes the arguments to be printed as described by printf.  In this
	      case, any e, n, r, R options are ignored.  Otherwise, unless the -C, -R, -r, or  -v
	      are specified, the following escape conventions will be applied:
	      \a     The alert character (ascii 07).
	      \b     The backspace character (ascii 010).
	      \c     Causes  print to end without processing more arguments and not adding a new-
		     line.
	      \f     The formfeed character (ascii 014).
	      \n     The new-line character (ascii 012).
	      \r     The carriage return character (ascii 015).
	      \t     The tab character (ascii 011).
	      \v     The vertical tab character (ascii 013).
	      \E     The escape character (ascii 033).
	      \\     The backslash character \.
	      \0x    The character defined by the 1, 2, or 3-digit octal string given by x.

	      The -R option will print all subsequent arguments and options other than	-n.   The
	      -e  causes  the above escape conventions to be applied.  This is the default behav-
	      ior.  It reverses the effect of an earlier -r.  The -p option causes the	arguments
	      to be written onto the pipe of the process spawned with |& instead of standard out-
	      put.  The -v option treats each arg as a variable name and writes the value in  the
	      printf  %B format.  The -C option treats each arg as a variable name and writes the
	      value in the printf %#B format.  The -s option causes the arguments to  be  written
	      onto  the  history  file	instead of standard output.  The -u option can be used to
	      specify a one digit file descriptor unit number unit on which the  output  will  be
	      placed.	The  default is 1.  If the option -n is used, no new-line is added to the
	      output.

       printf format [ arg ... ]
	      The arguments arg are printed on standard output in accordance with the ANSI-C for-
	      matting rules associated with the format string format.  If the number of arguments
	      exceeds the number of format specifications, the format string is reused to  format
	      remaining arguments.  The following extensions can also be used:
	      %b     A	%b format can be used instead of %s to cause escape sequences in the cor-
		     responding arg to be expanded as described in print.
	      %B     A %B option causes each of the arguments to be treated as variable names and
		     the binary value of variable will be printed.  The alternate flag # causes a
		     compound variable to be output on a single line.  This is	most  useful  for
		     compound variables and variables whose attribute is -b.
	      %H     A	%H  format  can be used instead of %s to cause characters in arg that are
		     special in HTML and XML to be output as their entity  name.   The	alternate
		     flag # formats the output for use as a URI.
	      %P     A	%P  format can be used instead of %s to cause arg to be interpreted as an
		     extended regular expression and be printed as a shell pattern.
	      %R     A %R format can be used instead of %s to cause arg to be  interpreted  as	a
		     shell pattern and to be printed as an extended regular expression.
	      %q     A	%q  format  can be used instead of %s to cause the resulting string to be
		     quoted in a manner than can be reinput to the shell.  When q is preceded  by
		     the alternative format specifier, #, the string is quoted in manner suitable
		     as a field in a .csv format file.
	      %(date-format)T
		     A %(date-format)T format can be use to treat  an  argument  as  a	date/time
		     string  and  to format the date/time according to the date-format as defined
		     for the date(1) command.
	      %Z     A %Z format will output a byte whose value is 0.
	      %d     The precision field of the %d format can be followed by a .  and the  output
		     base.  In this case, the # flag character causes base# to be prepended.
	      #      The  #  flag,  when used with the %d format without an output base, displays
		     the output in powers of 1000 indicated by one of the following suffixes: k M
		     G	T  P E, and when used with the %i format displays the output in powers of
		     1024 indicated by one of the following suffixes: Ki Mi Gi Ti Pi Ei.
	      =      The = flag centers the output within the specified field width.
	      L      The L flag, when used with the %c or %s formats, treats precision as charac-
		     ter width instead of byte count.
	      ,      The  , flag, when used with the %d or %f formats, separates groups of digits
		     with the grouping delimiter (, on groups of 3 in the C locale.)

       pwd [ -LP ]
	      Outputs the value of the current working directory.  The -L option is the  default;
	      it  prints  the  logical name of the current directory.  If the -P option is given,
	      all symbolic links are resolved from the name.  The last instance of -L  or  -P  on
	      the command line determines which method is used.

       read  [ -ACSprsv ] [ -d delim] [ -n n] [ [ -N n] [ [ -t timeout] [ -u unit] [ vname?prompt
       ] [ vname ... ]
	      The shell input mechanism.  One line is read and is broken up into fields using the
	      characters  in  IFS  as separators.  The escape character, \, is used to remove any
	      special meaning for the next character and for line continuation.   The  -d  option
	      causes  the  read to continue to the first character of delim rather than new-line.
	      The -n option causes at most n bytes to read rather a full  line	but  will  return
	      when  reading  from a slow device as soon as any characters have been read.  The -N
	      option causes exactly n to be read unless an end-of-file has  been  encountered  or
	      the  read  times out because of the -t option.  In raw mode, -r, the \ character is
	      not treated specially.  The first field is assigned to the first vname, the  second
	      field  to  the second vname, etc., with leftover fields assigned to the last vname.
	      When vname has the binary attribute and -n or -N is specified, the bytes	that  are
	      read are stored directly into the variable.  If the -v is specified, then the value
	      of the first vname will be used as a default value when  reading	from  a  terminal
	      device.  The -A option causes the variable vname to be unset and each field that is
	      read to be stored in successive elements of the indexed array vname.  The -C option
	      causes  the  variable  vname  to	be  read  as a compound variable.  Blanks will be
	      ignored when finding the beginning open parenthesis.  The -S option causes the line
	      to be treated like a record in a .csv format file so that double quotes can be used
	      to allow the delimiter character and the new-line  character  to	appear	within	a
	      field.   The  -p	option causes the input line to be taken from the input pipe of a
	      process spawned by the shell using |&.  If the -s option is present, the input will
	      be  saved as a command in the history file.  The option -u can be used to specify a
	      one digit file descriptor unit unit to read  from.   The	file  descriptor  can  be
	      opened  with  the exec special built-in command.	The default value of unit n is 0.
	      The option -t is used to specify a timeout in seconds when reading from a  terminal
	      or pipe.	If vname is omitted, then REPLY is used as the default vname.  An end-of-
	      file with the -p option causes cleanup for this process  so  that  another  can  be
	      spawned.	If the first argument contains a ?, the remainder of this word is used as
	      a prompt on standard error when the shell is interactive.  The  exit  status  is	0
	      unless an end-of-file is encountered or read has timed out.

       -- readonly [ -p ] [ vname[=value] ] ...
	      If  vname  is  not  given,  the names and values of each variable with the readonly
	      attribute is printed with the values quoted in a manner that allows them to be  re-
	      inputted.   The  -p option causes the word readonly to be inserted before each one.
	      Otherwise, the given vnames are marked readonly and these names cannot  be  changed
	      by  subsequent  assignment.   When defining a type, if the value of a readonly sub-
	      variable is not defined the value is required when creating each instance.

       - return [ n ]
	      Causes a shell function or .  script to return to the invoking script with the exit
	      status specified by n.  The value will be the least significant 8 bits of the spec-
	      ified status.  If n is omitted, then the return status is that of the last  command
	      executed.   If  return  is  invoked while not in a function or a .  script, then it
	      behaves the same as exit.

       - set [ +-BCGabefhkmnoprstuvx ] [ +-o [ option ] ] ... [ +-A vname ]  [ arg ... ]
	      The options for this command have meaning as follows:
	      -A      Array assignment.  Unset the variable vname and assign values  sequentially
		      from the arg list.  If +A is used, the variable vname is not unset first.
	      -B      Enable brace pattern field generation.  This is the default behavior.
	      -B      Enable brace group expansion.  On by default.
	      -C      Prevents redirection > from truncating existing files.  Files that are cre-
		      ated are opened with the O_EXCL mode.  Requires >| to truncate a file  when
		      turned on.
	      -G      Causes the pattern ** by itself to match files and zero or more directories
		      and sub-directories when used for file name generation.  If followed by a /
		      only directories and sub-directories are matched.
	      -a      All subsequent variables that are defined are automatically exported.
	      -b      Prints  job  completion  messages as soon as a background job changes state
		      rather than waiting for the next prompt.
	      -e      Unless contained in a || or && command, or  the  command	following  an  if
		      while  or  until command or in the pipeline following !, if a command has a
		      non-zero exit status, execute the ERR trap, if set, and exit.  This mode is
		      disabled while reading profiles.
	      -f      Disables file name generation.
	      -h      Each command becomes a tracked alias when first encountered.
	      -k      (Obsolete). All variable assignment arguments are placed in the environment
		      for a command, not just those that precede the command name.
	      -m      Background jobs will run in a separate process group and a line will  print
		      upon  completion.  The exit status of background jobs is reported in a com-
		      pletion message.	On systems with job control, this  option  is  turned  on
		      automatically for interactive shells.
	      -n      Read  commands  and  check them for syntax errors, but do not execute them.
		      Ignored for interactive shells.
	      -o      The following argument can be one of the following option names:
		      allexport
			      Same as -a.
		      errexit Same as -e.
		      bgnice  All background jobs are run at  a  lower	priority.   This  is  the
			      default mode.
		      braceexpand
			      Same as -B.
		      emacs   Puts you in an emacs style in-line editor for command entry.
		      globstar
			      Same as -G.
		      gmacs   Puts you in a gmacs style in-line editor for command entry.
		      ignoreeof
			      The  shell  will not exit on end-of-file.  The command exit must be
			      used.
		      keyword Same as -k.
		      letoctal
			      The let command allows octal constants starting with 0.
		      markdirs
			      All directory names resulting from  file	name  generation  have	a
			      trailing / appended.
		      monitor Same as -m.
		      multiline
			      The  built-in  editors  will  use  multiple lines on the screen for
			      lines that are longer than the width of the screen.  This  may  not
			      work for all terminals.
		      noclobber
			      Same as -C.
		      noexec  Same as -n.
		      noglob  Same as -f.
		      nolog   Do not save function definitions in the history file.
		      notify  Same as -b.
		      nounset Same as -u.
		      pipefail
			      A  pipeline  will not complete until all components of the pipeline
			      have completed, and the return value will be the value of the  last
			      non-zero command to fail or zero if no command has failed.
		      showme  When  enabled, simple commands or pipelines preceded by a semicolon
			      (;) will be displayed as if the xtrace option were enabled but will
			      not be executed.	Otherwise, the leading ; will be ignored.
		      privileged
			      Same as -p.
		      verbose Same as -v.
		      trackall
			      Same as -h.
		      vi      Puts  you in insert mode of a vi style in-line editor until you hit
			      the escape character 033.  This puts you in control mode.  A return
			      sends the line.
		      viraw   Each character is processed as it is typed in vi mode.
		      xtrace  Same as -x.
		      If  no  option  name  is	supplied,  then  the  current option settings are
		      printed.
	      -p      Disables	processing  of	the  $HOME/.profile  file  and	uses   the   file
		      /etc/suid_profile  instead  of  the ENV file.  This mode is on whenever the
		      effective uid (gid) is not equal to the real uid (gid).  Turning	this  off
		      causes the effective uid and gid to be set to the real uid and gid.
	      -r      Enables the restricted shell.  This option cannot be unset once set.
	      -s      Sort the positional parameters lexicographically.
	      -t      (Obsolete).  Exit after reading and executing one command.
	      -u      Treat unset parameters as an error when substituting.
	      -v      Print shell input lines as they are read.
	      -x      Print commands and their arguments as they are executed.
	      --      Do not change any of the options; useful in setting $1 to a value beginning
		      with -.  If no arguments follow this option then the positional  parameters
		      are unset.

	      As an obsolete feature, if the first arg is - then the -x and -v options are turned
	      off and the next arg is treated as the first  argument.	Using  +  rather  than	-
	      causes these options to be turned off.  These options can also be used upon invoca-
	      tion of the shell.  The current set of options may be found in $-.   Unless  -A  is
	      specified,  the  remaining arguments are positional parameters and are assigned, in
	      order, to $1 $2 ....  If no arguments are given, then the names and values  of  all
	      variables are printed on the standard output.

       - shift [ n ]
	      The  positional parameters from $n+1 ...	are renamed $1 ... , default n is 1.  The
	      parameter n can be any arithmetic expression that evaluates to a non-negative  num-
	      ber less than or equal to $#.

       sleep seconds
	      Suspends execution for the number of decimal seconds or fractions of a second given
	      by seconds.

       - trap [ -p ] [ action ] [ sig ] ...
	      The -p option causes the trap action associated with each trap as specified by  the
	      arguments  to  be printed with appropriate quoting.  Otherwise, action will be pro-
	      cessed as if it were an argument to eval when the  shell	receives  signal(s)  sig.
	      Each  sig can be given as a number or as the name of the signal.	Trap commands are
	      executed in order of signal number.  Any attempt to set a trap on a signal that was
	      ignored on entry to the current shell is ineffective.  If action is omitted and the
	      first sig is a number, or if action is -, then the trap(s) for each sig  are  reset
	      to their original values.  If action is the null string then this signal is ignored
	      by the shell and by the commands it invokes.  If sig is ERR  then  action  will  be
	      executed	whenever  a  command  has  a  non-zero exit status.  If sig is DEBUG then
	      action will be executed before each command.  The variable .sh.command will contain
	      the  contents of the current command line when action is running.  If the exit sta-
	      tus of the trap is 2 the command will not be executed.  If the exit status  of  the
	      trap  is 255 and inside a function or a dot script, the function or dot script will
	      return.  If sig is 0 or EXIT and the trap statement is executed inside the body  of
	      a  function  defined with the function name syntax, then the command action is exe-
	      cuted after the function completes.  If sig is 0 or EXIT for a trap set outside any
	      function	then  the  command  action is executed on exit from the shell.	If sig is
	      KEYBD, then action will be executed whenever a key is read while in  emacs,  gmacs,
	      or  vi  mode.  The trap command with no arguments prints a list of commands associ-
	      ated with each signal number.

       An exit or return without an argument in a trap action will preserve the  exit  status  of
       the command that invoked the trap.

       true   Does nothing, and exits 0. Used with while for infinite loops.

       --  typeset  [  +-ACHSfblmnprtux  ]  [  +-EFLRXZi[n]  ]	  [  +-M   [  mapname ] ] [ -T	[
       tname=(assign_list) ] ] [ -h str ] [ -a [type] ] [ vname[=value ]  ] ...
	      Sets attributes and values for shell variables and functions.  When invoked  inside
	      a  function  defined  with the function name syntax, a new instance of the variable
	      vname is created, and the variable's value and type are restored when the  function
	      completes.  The following list of attributes may be specified:
	      -A     Declares  vname  to  be an associative array.  Subscripts are strings rather
		     than arithmetic expressions.
	      -C     causes each vname to be a compound variable.  value names a  compound  vari-
		     able it is copied into vname.  Otherwise, it unsets each vname.
	      -a     Declares vname to be an indexed array.  If type is specified, it must be the
		     name of an enumeration type created with the enum command and it allows enu-
		     meration constants to be used as subscripts.
	      -E     Declares vname to be a double precision floating point number.  If n is non-
		     zero, it defines the number  of  significant  figures  that  are  used  when
		     expanding vname.  Otherwise, ten significant figures will be used.
	      -F     Declares vname to be a double precision floating point number.  If n is non-
		     zero, it defines the number of places after the decimal point that are  used
		     when  expanding vname.  Otherwise ten places after the decimal point will be
		     used.
	      -H     This option provides UNIX to host-name file mapping on non-UNIX machines.
	      -L     Left justify and remove leading blanks from value.  If  n	is  non-zero,  it
		     defines  the  width of the field, otherwise it is determined by the width of
		     the value of first assignment.  When the variable	is  assigned  to,  it  is
		     filled  on the right with blanks or truncated, if necessary, to fit into the
		     field.  The -R option is turned off.
	      -M     Use the character mapping mapping defined by wctrans(3).	such  as  tolower
		     and  toupper when assigning a value to each of the specified operands.  When
		     mapping is specified and there are not operands, all variables that use this
		     mapping  are  written to standard output.	When mapping is omitted and there
		     are no operands, all mapped variables are written to standard output.
	      -R     Right justify and fill with leading blanks.  If n is  non-zero,  it  defines
		     the width of the field, otherwise it is determined by the width of the value
		     of first assignment.  The field is left filled with blanks or truncated from
		     the end if the variable is reassigned.  The -L option is turned off.
	      -S     When  used within the assign_list of a type definition, it causes the speci-
		     fied sub-variable to be shared by all instances  of  the  type.   When  used
		     inside  a	function  defined  with the function reserved word, the specified
		     variables will have function static scope.  Otherwise, the variable is unset
		     prior to processing the assignment list.
	      -T     If  followed  by  tname, it creates a type named by tname using the compound
		     assignment assign_list to tname.  Otherwise, it writes all the type  defini-
		     tions to standard output.
	      -X     Declares  vname  to  be a double precision floating point number and expands
		     using the %a format of ISO-C99.  If n is non-zero, it defines the number  of
		     hex  digits  after  the  radix point that is used when expanding vname.  The
		     default is 10.
	      -Z     Right justify and fill with leading zeros if the first  non-blank	character
		     is  a digit and the -L option has not been set.  Remove leading zeros if the
		     -L option is also set.  If n is non-zero, it defines the width of the field,
		     otherwise it is determined by the width of the value of first assignment.
	      -f     The  names  refer	to function names rather than variable names.  No assign-
		     ments can be made and the only other valid options are -S, -t,  -u  and  -x.
		     The  -S  can be used with discipline functions defined in a type to indicate
		     that the function is static.  For a static function, the same method will be
		     used  by  all instances of that type no matter which instance references it.
		     In addition, it can only use value of variables from the original type defi-
		     nition.   These  discipline  functions  cannot  be  redefined  in	any  type
		     instance.	The -t option turns on execution tracing for this function.   The
		     -u  option  causes this function to be marked undefined.  The FPATH variable
		     will be searched to find the function definition when the function is refer-
		     enced.   If no options other than -f is specified, then the function defini-
		     tion will be displayed on standard output.  If +f is specified, then a  line
		     containing the function name followed by a shell comment containing the line
		     number and path name of the file where this function was defined, if any, is
		     displayed.  The exit status can be used to determine whether the function is
		     defined so that typeset -f .sh.math.name will return 0  when  math  function
		     name is defined and non-zero otherwise.
	      -b     The  variable can hold any number of bytes of data.  The data can be text or
		     binary.  The value is represented by the base64 encoding of the data.  If -Z
		     is  also  specified,  the	size  in  bytes of the data in the buffer will be
		     determined by the size  associated  with  the  -Z.   If  the  base64  string
		     assigned  results in more data, it will be truncated.  Otherwise, it will be
		     filled with bytes whose value is zero.  The printf format %B can be used  to
		     output  the actual data in this buffer instead of the base64 encoding of the
		     data.
	      -h     Used within type definitions to add information when generating  information
		     about  the sub-variable on the man page.  It is ignored when used outside of
		     a type definition.  When used with -f the information is associated with the
		     corresponding discipline function.
	      -i     Declares vname to be represented internally as integer.  The right hand side
		     of an assignment is evaluated as an arithmetic expression when assigning  to
		     an integer.  If n is non-zero, it defines the output arithmetic base, other-
		     wise the output base will be ten.
	      -l     Used with -i, -E or -F, to indicate long integer, or long float.  Otherwise,
		     all  upper-case  characters  are  converted  to  lower-case.  The upper-case
		     option, -u, is turned off.  Equivalent to -M tolower .
	      -m     moves or renames the variable.  The value is the name of  a  variable  whose
		     value  will be moved to vname.  The original variable will be unset.  Cannot
		     be used with any other options.
	      -n     Declares vname to be a reference to the variable whose name  is  defined  by
		     the  value  of variable vname.  This is usually used to reference a variable
		     inside a function whose name has been passed as an argument.  Cannot be used
		     with any other options.
	      -p     The name, attributes and values for the given vnames are written on standard
		     output in a form that can be used as shell input.	If +p is specified,  then
		     the values are not displayed.
	      -r     The  given  vnames  are marked readonly and these names cannot be changed by
		     subsequent assignment.
	      -t     Tags the variables.  Tags are user definable and have no special meaning  to
		     the shell.
	      -u     When given along with -i, specifies unsigned integer.  Otherwise, all lower-
		     case characters are converted to upper-case.  The lower-case option, -l,  is
		     turned off.  Equivalent to -M toupper .
	      -x     The  given vnames are marked for automatic export to the environment of sub-
		     sequently-executed commands.  Variables whose names contain a .   cannot  be
		     exported.

	      The -i attribute cannot be specified along with -R, -L, -Z, or -f.

	      Using + rather than - causes these options to be turned off.  If no vname arguments
	      are given, a list of vnames  (and  optionally  the  values)  of  the  variables  is
	      printed.	 (Using  +  rather  than  - keeps the values from being printed.)  The -p
	      option causes typeset followed by the option letters to be printed before each name
	      rather  than  the names of the options.  If any option other than -p is given, only
	      those variables which have all of the given options are  printed.   Otherwise,  the
	      vnames and attributes of all variables that have attributes are printed.

       ulimit [ -HSacdfmnpstv ] [ limit ]
	      Set  or  display a resource limit.  The available resource limits are listed below.
	      Many systems do not support one or more of these limits.	The limit for a specified
	      resource is set when limit is specified.	The value of limit can be a number in the
	      unit specified below with each resource, or the value unlimited.	 The  -H  and  -S
	      options  specify whether the hard limit or the soft limit for the given resource is
	      set.  A hard limit cannot be increased once  it  is  set.   A  soft  limit  can  be
	      increased  up  to  the  value  of the hard limit.  If neither the H nor S option is
	      specified, the limit applies to both.  The current resource limit is  printed  when
	      limit  is  omitted.  In this case, the soft limit is printed unless H is specified.
	      When more than one resource is specified, then the limit name and unit  is  printed
	      before the value.
	      -a     Lists all of the current resource limits.
	      -c     The number of 512-byte blocks on the size of core dumps.
	      -d     The number of K-bytes on the size of the data area.
	      -f     The  number  of  512-byte blocks on files that can be written by the current
		     process or by child processes (files of any size may be read).
	      -m     The number of K-bytes on the size of physical memory.
	      -n     The number of file descriptors plus 1.
	      -p     The number of 512-byte blocks for pipe buffering.
	      -s     The number of K-bytes on the size of the stack area.
	      -t     The number of CPU seconds to be used by each process.
	      -v     The number of K-bytes for virtual memory.

	      If no option is given, -f is assumed.

       umask [ -S ] [ mask ]
	      The user file-creation mask is set to mask (see umask(2)).  mask can either  be  an
	      octal  number or a symbolic value as described in chmod(1).  If a symbolic value is
	      given, the new umask value is the complement of the result of applying mask to  the
	      complement  of  the previous umask value.  If mask is omitted, the current value of
	      the mask is printed.  The -S option causes the mode to be  printed  as  a  symbolic
	      value.  Otherwise, the mask is printed in octal.

       - unalias [ -a ] name ...
	      The  aliases  given  by  the list of names are removed from the alias list.  The -a
	      option causes all the aliases to be unset.

       -unset [ -fnv ] vname ...
	      The variables given by the list of vnames are unassigned,  i.e.,	except	for  sub-
	      variables within a type, their values and attributes are erased.	For sub-variables
	      of a type, the values are reset to the default  value  from  the	type  definition.
	      Readonly	variables cannot be unset.  If the -f option is set, then the names refer
	      to function names.  If the -v option is set,  then  the  names  refer  to  variable
	      names.   The  -f	option	overrides -v.  If -n is set and name is a name reference,
	      then name will be unset rather than the variable that it references.   The  default
	      is equivalent to -v.  Unsetting LINENO, MAILCHECK, OPTARG, OPTIND, RANDOM, SECONDS,
	      TMOUT, and _ removes their special meaning even if they are  subsequently  assigned
	      to.

       wait [ job ... ]
	      Wait for the specified job and report its termination status.  If job is not given,
	      then all currently active child processes are waited for.   The  exit  status  from
	      this  command is that of the last process waited for if job is specified; otherwise
	      it is zero.  See Jobs for a description of the format of job.

       whence [ -afpv ] name ...
	      For each name, indicate how it would be interpreted if used as a command name.
	      The -v option produces a more verbose report.  The -f option skips the  search  for
	      functions.   The	-p option does a path search for name even if name is an alias, a
	      function, or a reserved word.  The -p option turns  off  the  -v	option.   The  -a
	      option is similar to the -v option but causes all interpretations of the given name
	      to be reported.

   Invocation.
       If the shell is invoked by exec(2), and the first character of argument zero  ($0)  is  -,
       then  the shell is assumed to be a login shell and commands are read from /etc/profile and
       then from either .profile in the current  directory  or	$HOME/.profile,  if  either  file
       exists.	Next, for interactive shells, commands are read from the file named by performing
       parameter expansion, command substitution, and arithmetic substitution on the value of the
       environment  variable ENV if the file exists.  If the -s option is not present and arg and
       a file by the name of arg exists, then it reads and executes this script.   Otherwise,  if
       the  first arg does not contain a /, a path search is performed on the first arg to deter-
       mine the name of the script to execute.	The script arg must have execute  permission  and
       any  setuid  and setgid settings will be ignored.  If the script is not found on the path,
       arg is processed as if it named a built-in command or function.	Commands are then read as
       described below; the following options are interpreted by the shell when it is invoked:

       -D      Do not execute the script, but output the set of double quoted strings preceded by
	       a $.  These strings are	needed	for  localization  of  the  script  to	different
	       locales.
       -E      Reads  the  file named by the ENV variable or by $HOME/.kshrc if not defined after
	       the profiles.
       -c	 If the -c option is present, then commands are read from  the	first  arg.   Any
		 remaining arguments become positional parameters starting at 0.
       -s	 If  the  -s  option is present or if no arguments remain, then commands are read
		 from the standard input.  Shell output, except for the  output  of  the  Special
		 Commands listed above, is written to file descriptor 2.
       -i	 If  the -i option is present or if the shell input and error output are attached
		 to a terminal (as told by tcgetattr(2)), then this  shell  is	interactive.   In
		 this  case  TERM  is ignored (so that kill 0 does not kill an interactive shell)
		 and INTR is caught and ignored (so that wait  is  ).	In  all  cases,  QUIT  is
		 ignored by the shell.
       -r	 If the -r option is present, the shell is a restricted shell.
       -D	 A  list of all double quoted strings that are preceded by a $ will be printed on
		 standard output and the shell will exit.  This set of strings will be subject to
		 language  translation	when  the  locale is not C or POSIX.  No commands will be
		 executed.

       -P	 If -P or -o profile is present, the shell is a profile shell (see pfexec(1)).

       -R filename
		 The -R filename option is used to generate a cross reference database	that  can
		 be  used  by a separate utility to find definitions and references for variables
		 and commands.	The filename argument specifies the generated database. A  script
		 file must be provided on the command line as well.

       The  remaining  options	and  arguments	are  described	under  the set command above.  An
       optional - as the first argument is ignored.

   Rksh Only.
       Rksh is used to set up login names and execution environments whose capabilities are  more
       controlled  than  those of the standard shell.  The actions of rksh are identical to those
       of ksh, except that the following are disallowed:
	      Unsetting the restricted option.
	      changing directory (see cd(1)),
	      setting or unsetting the value or attributes of SHELL, ENV, FPATH, or PATH,
	      specifying path or command names containing /,
	      redirecting output (>, >|, <>, and >>).
	      adding or deleting built-in commands.
	      using command -p to invoke a command.

       The restrictions above are enforced after .profile and the ENV files are interpreted.

       When a command to be executed is found to be a shell procedure, rksh invokes ksh  to  exe-
       cute  it.   Thus,  it  is  possible  to provide to the end-user shell procedures that have
       access to the full power of the standard shell, while imposing a limited menu of commands;
       this  scheme  assumes that the end-user does not have write and execute permissions in the
       same directory.

       The net effect of these rules is that the writer of the .profile has complete control over
       user  actions, by performing guaranteed setup actions and leaving the user in an appropri-
       ate directory (probably not the login directory).

       The system administrator often sets up a directory of commands (e.g., /usr/rbin) that  can
       be safely invoked by rksh.

EXIT STATUS
       Errors  detected by the shell, such as syntax errors, cause the shell to return a non-zero
       exit status.  If the shell is being used non-interactively, then execution  of  the  shell
       file  is abandoned unless the error occurs inside a subshell in which case the subshell is
       abandoned.  Otherwise, the shell returns the exit status of the last command executed (see
       also  the  exit	command  above).   Run	time errors detected by the shell are reported by
       printing the command or function name and the error condition.  If the  line  number  that
       the  error occurred on is greater than one, then the line number is also printed in square
       brackets ([]) after the command or function name.

FILES
       /etc/profile
	      The system wide initialization file, executed for login shells.

       $HOME/.profile
	      The personal initialization file, executed for login shells after /etc/profile.

       $HOME/..kshrc
	      Default personal initialization file, executed for interactive shells when  ENV  is
	      not set.

       /etc/suid_profile
	      Alternative  initialization  file,  executed instead of the personal initialization
	      file when the real and effective user or group id do not match.

       /dev/null
	      NULL device

SEE ALSO
       cat(1), cd(1), chmod(1), cut(1), egrep(1), echo(1), emacs(1), env(1), fgrep(1),	gmacs(1),
       grep(1),  newgrp(1),  pfexec(1),  stty(1),  test(1),  umask(1),	vi(1),	dup(2),  exec(2),
       fork(2), getpwnam(3), ioctl(2),	lseek(2),  paste(1),  pathconf(2),  pipe(2),  sysconf(2),
       umask(2), ulimit(2), wait(2), wctrans(3), rand(3), a.out(5), profile(5), environ(7).

       Morris  I.  Bolsky  and David G. Korn, The New KornShell Command and Programming Language,
       Prentice Hall, 1995.

       POSIX - Part 2: Shell and Utilities, IEEE Std 1003.2-1992, ISO/IEC 9945-2, IEEE, 1993.

CAVEATS
       If a command is executed, and then a command with the same name is installed in	a  direc-
       tory  in  the  search  path before the directory where the original command was found, the
       shell will continue to exec the original command.  Use the -t option of the alias  command
       to correct this situation.

       Some very old shell scripts contain a ^ as a synonym for the pipe character |.

       Using  the hist built-in command within a compound command will cause the whole command to
       disappear from the history file.

       The built-in command . file reads the whole file before any commands are executed.  There-
       fore, alias and unalias commands in the file will not apply to any commands defined in the
       file.

       Traps are not processed while a job is waiting for a foreground process.  Thus, a trap  on
       CHLD won't be executed until the foreground job terminates.

       It  is  a good idea to leave a space after the comma operator in arithmetic expressions to
       prevent the comma from being  interpreted  as  the  decimal  point  character  in  certain
       locales.

											   KSH(1)
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