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Linux 2.6 - man page for ed (linux section 1posix)

ED(P)				    POSIX Programmer's Manual				    ED(P)

NAME
       ed - edit text

SYNOPSIS
       ed [-p string][-s][file]

DESCRIPTION
       The  ed utility is a line-oriented text editor that uses two modes: command mode and input
       mode. In command mode the input characters shall be interpreted as commands, and in  input
       mode they shall be interpreted as text. See the EXTENDED DESCRIPTION section.

OPTIONS
       The  ed utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, Sec-
       tion 12.2, Utility Syntax Guidelines.

       The following options shall be supported:

       -p  string
	      Use string as the prompt string when in command mode. By default, there shall be no
	      prompt string.

       -s     Suppress	the  writing  of  byte	counts	by e, E, r, and w commands and of the '!'
	      prompt after a !command.

OPERANDS
       The following operand shall be supported:

       file   If the file argument is given, ed shall simulate an e command on the file named  by
	      the  pathname, file, before accepting commands from the standard input. If the file
	      operand is '-' , the results are unspecified.

STDIN
       The standard input shall be a text file	consisting  of	commands,  as  described  in  the
       EXTENDED DESCRIPTION section.

INPUT FILES
       The input files shall be text files.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of ed:

       HOME   Determine the pathname of the user's home directory.

       LANG   Provide  a  default  value for the internationalization variables that are unset or
	      null. (See the Base Definitions volume of IEEE Std 1003.1-2001, Section 8.2, Inter-
	      nationalization Variables for the precedence of internationalization variables used
	      to determine the values of locale categories.)

       LC_ALL If set to a non-empty string value, override the values of all the  other  interna-
	      tionalization variables.

       LC_COLLATE

	      Determine  the  locale  for the behavior of ranges, equivalence classes, and multi-
	      character collating elements within regular expressions.

       LC_CTYPE
	      Determine the locale for the interpretation of sequences of bytes of text  data  as
	      characters  (for	example, single-byte as opposed to multi-byte characters in argu-
	      ments and input files) and the behavior of character classes within regular expres-
	      sions.

       LC_MESSAGES
	      Determine the locale that should be used to affect the format and contents of diag-
	      nostic messages written to standard error and informative messages written to stan-
	      dard output.

       NLSPATH
	      Determine the location of message catalogs for the processing of LC_MESSAGES .

ASYNCHRONOUS EVENTS
       The ed utility shall take the standard action for all signals (see the ASYNCHRONOUS EVENTS
       section in Utility Description Defaults ) with the following exceptions:

       SIGINT The ed utility shall interrupt its current activity,  write  the	string	"?\n"  to
	      standard output, and return to command mode (see the EXTENDED DESCRIPTION section).

       SIGHUP If  the  buffer  is  not empty and has changed since the last write, the ed utility
	      shall attempt to write a copy of the buffer in a file. First, the file named ed.hup
	      in the current directory shall be used; if that fails, the file named ed.hup in the
	      directory named by the HOME environment variable shall be used. In any case, the ed
	      utility shall exit without returning to command mode.

       SIGQUIT
	      The ed utility shall ignore this event.

STDOUT
       Various	editing  commands and the prompting feature (see -p) write to standard output, as
       described in the EXTENDED DESCRIPTION section.

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       The output files shall be text files whose formats are dependent on the	editing  commands
       given.

EXTENDED DESCRIPTION
       The ed utility shall operate on a copy of the file it is editing; changes made to the copy
       shall have no effect on the file until a w (write) command is given. The copy of the  text
       is called the buffer.

       Commands  to  ed have a simple and regular structure: zero, one, or two addresses followed
       by a single-character command, possibly followed by  parameters	to  that  command.  These
       addresses  specify  one or more lines in the buffer. Every command that requires addresses
       has default addresses, so that the addresses very often can be omitted. If the  -p  option
       is specified, the prompt string shall be written to standard output before each command is
       read.

       In general, only one command can appear on a line.  Certain  commands  allow  text  to  be
       input.  This  text is placed in the appropriate place in the buffer. While ed is accepting
       text, it is said to be in input mode. In this mode, no commands shall be  recognized;  all
       input  is  merely collected. Input mode is terminated by entering a line consisting of two
       characters: a period ( '.' ) followed by a <newline>. This line is not considered part  of
       the input text.

   Regular Expressions in ed
       The  ed	utility shall support basic regular expressions, as described in the Base Defini-
       tions volume of IEEE Std 1003.1-2001, Section 9.3, Basic Regular Expressions. Since  regu-
       lar  expressions  in ed are always matched against single lines (excluding the terminating
       <newline>s), never against any larger section of text, there  is  no  way  for  a  regular
       expression to match a <newline>.

       A null RE shall be equivalent to the last RE encountered.

       Regular	expressions  are  used	in  addresses to specify lines, and in some commands (for
       example, the s substitute command) to specify portions of a line to be substituted.

   Addresses in ed
       Addressing in ed relates to the current line. Generally, the current line is the last line
       affected  by a command. The current line number is the address of the current line. If the
       edit buffer is not empty, the initial value for the current line shall be the last line in
       the edit buffer; otherwise, zero.

       Addresses shall be constructed as follows:

	1. The period character ( '.' ) shall address the current line.

	2. The dollar sign character ( '$' ) shall address the last line of the edit buffer.

	3. The positive decimal number n shall address the nth line of the edit buffer.

	4. The	apostrophe-x  character pair ( "'x" ) shall address the line marked with the mark
	   name character x, which shall be a lowercase letter from the portable  character  set.
	   It  shall  be an error if the character has not been set to mark a line or if the line
	   that was marked is not currently present in the edit buffer.

	5. A BRE enclosed by slash characters ( '/' ) shall  address  the  first  line	found  by
	   searching forwards from the line following the current line toward the end of the edit
	   buffer and stopping at the first line for which the	line  excluding  the  terminating
	   <newline>  matches  the  BRE.  The BRE consisting of a null BRE delimited by a pair of
	   slash characters shall address the next line for which the line excluding  the  termi-
	   nating  <newline>  matches the last BRE encountered. In addition, the second slash can
	   be omitted at the end of a command line. Within the BRE, a backslash-slash pair ( "\/"
	   )  shall  represent	a  literal  slash instead of the BRE delimiter. If necessary, the
	   search shall wrap around to the beginning of the buffer and continue up to and includ-
	   ing the current line, so that the entire buffer is searched.

	6. A  BRE enclosed by question-mark characters ( '?' ) shall address the first line found
	   by searching backwards from the line preceding the current line toward  the	beginning
	   of  the  edit  buffer  and stopping at the first line for which the line excluding the
	   terminating <newline> matches the BRE. The BRE consisting of a null BRE delimited by a
	   pair  of  question-mark  characters ( "??" ) shall address the previous line for which
	   the line excluding the terminating <newline> matches  the  last  BRE  encountered.  In
	   addition, the second question-mark can be omitted at the end of a command line. Within
	   the BRE, a backslash-question-mark pair ( "\?" ) shall represent  a	literal  question
	   mark  instead  of the BRE delimiter. If necessary, the search shall wrap around to the
	   end of the buffer and continue up to and including  the  current  line,  so	that  the
	   entire buffer is searched.

	7. A  plus-sign  (  '+'  ) or hyphen character ( '-' ) followed by a decimal number shall
	   address the current line plus or minus the number. A plus-sign or hyphen character not
	   followed by a decimal number shall address the current line plus or minus 1.

       Addresses  can  be followed by zero or more address offsets, optionally <blank>-separated.
       Address offsets are constructed as follows:

	* A plus-sign or hyphen character followed by a decimal number	shall  add  or	subtract,
	  respectively,  the  indicated  number  of  lines to or from the address. A plus-sign or
	  hyphen character not followed by a decimal number shall add or subtract 1  to  or  from
	  the address.

	* A decimal number shall add the indicated number of lines to the address.

       It shall not be an error for an intermediate address value to be less than zero or greater
       than the last line in the edit buffer. It shall be an error for the final address value to
       be  less  than zero or greater than the last line in the edit buffer. It shall be an error
       if a search for a BRE fails to find a matching line.

       Commands accept zero, one, or two addresses. If more than the required number of addresses
       are  provided  to a command that requires zero addresses, it shall be an error. Otherwise,
       if more than the required number of addresses are provided to  a  command,  the	addresses
       specified  first  shall	be evaluated and then discarded until the maximum number of valid
       addresses remain, for the specified command.

       Addresses shall be separated from each other by a comma ( ',' ) or semicolon  character	(
       ';'  ). In the case of a semicolon separator, the current line ( '.' ) shall be set to the
       first address, and only then will the second address be calculated. This  feature  can  be
       used  to determine the starting line for forwards and backwards searches; see rules 5. and
       6.

       Addresses can be omitted on either side of the comma or semicolon separator, in which case
       the resulting address pairs shall be as follows:

					Specified   Resulting
					,	    1 , $
					, addr	    1 , addr
					addr ,	    addr , addr
					;	    . ; $
					; addr	    . ; addr
					addr ;	    addr ; addr

       Any  <blank>s  included between addresses, address separators, or address offsets shall be
       ignored.

   Commands in ed
       In the following list of ed commands, the default addresses are shown in parentheses.  The
       number  of addresses shown in the default shall be the number expected by the command. The
       parentheses are not part of the address; they  show  that  the  given  addresses  are  the
       default.

       It  is generally invalid for more than one command to appear on a line.	However, any com-
       mand (except e, E, f, q, Q, r, w, and !) can be suffixed by the letter  l,  n,  or  p;  in
       which  case,  except  for the l, n, and p commands, the command shall be executed and then
       the new current line shall be written as described below under the l, n, and  p	commands.
       When  an  l, n, or p suffix is used with an l, n, or p command, the command shall write to
       standard output as described below, but it is unspecified whether the  suffix  writes  the
       current	line again in the requested format or whether the suffix has no effect. For exam-
       ple, the pl command (base p command with an l suffix) shall either write just the  current
       line  or write it twice-once as specified for p and once as specified for l.  Also, the g,
       G, v, and V commands shall take a command as a parameter.

       Each address component can be preceded by zero or more <blank>s. The command letter can be
       preceded by zero or more <blank>s. If a suffix letter ( l, n, or p) is given, the applica-
       tion shall ensure that it immediately follows the command.

       The e, E, f, r, and w commands shall take an optional file parameter, separated	from  the
       command letter by one or more <blank>s.

       If  changes  have  been	made in the buffer since the last w command that wrote the entire
       buffer, ed shall warn the user if an attempt is made to destroy the editor buffer via  the
       e or q commands. The ed utility shall write the string:

	      "?\n"

       (followed  by  an  explanatory message if help mode has been enabled via the H command) to
       standard output and shall continue in command mode with the current line number unchanged.
       If the e or q command is repeated with no intervening command, it shall take effect.

       If a terminal disconnect is detected:

	* If  the  buffer is not empty and has changed since the last write, the ed utility shall
	  attempt to write a copy of the buffer to a file named ed.hup in the current  directory.
	  If  this  write  fails,  ed  shall  attempt to write a copy of the buffer to a filename
	  ed.hup in the directory named by the HOME environment variable. If both these  attempts
	  fail, ed shall exit without saving the buffer.

	* The  ed utility shall not write the file to the currently remembered pathname or return
	  to command mode, and shall terminate with a non-zero exit status.

       If an end-of-file is detected on standard input:

	* If the ed utility is in input mode, ed shall terminate input mode and return to command
	  mode.  It  is unspecified if any partially entered lines (that is, input text without a
	  terminating <newline>) are discarded from the input text.

	* If the ed utility is in command mode, it shall act as if a q command had been entered.

       If the closing delimiter of an RE or of a replacement string (for example, '/' ) in  a  g,
       G,  s,  v, or V command would be the last character before a <newline>, that delimiter can
       be omitted, in which case the addressed line shall be written. For example, the	following
       pairs of commands are equivalent:

	      s/s1/s2	s/s1/s2/p
	      g/s1	g/s1/p
	      ?s1	?s1?

       If an invalid command is entered, ed shall write the string:

	      "?\n"

       (followed  by  an  explanatory message if help mode has been enabled via the H command) to
       standard output and shall continue in command mode with the current line number unchanged.

   Append Command
       Synopsis:

	      (.)a
	      <text>
	      .

       The a command shall read the given text and append it after the addressed line;	the  cur-
       rent  line  number  shall  become  the address of the last inserted line or, if there were
       none, the addressed line. Address 0 shall be valid for this command; it	shall  cause  the
       appended text to be placed at the beginning of the buffer.

   Change Command
       Synopsis:

	      (.,.)c
	      <text>
	      .

       The c command shall delete the addressed lines, then accept input text that replaces these
       lines; the current line shall be set to the address of the last line input; or,	if  there
       were  none,  at the line after the last line deleted; if the lines deleted were originally
       at the end of the buffer, the current line number shall be set to the address of  the  new
       last line; if no lines remain in the buffer, the current line number shall be set to zero.
       Address 0 shall be valid for this command; it shall be interpreted as if  address  1  were
       specified.

   Delete Command
       Synopsis:

	      (.,.)d

       The  d  command shall delete the addressed lines from the buffer.  The address of the line
       after the last line deleted shall become the current line number;  if  the  lines  deleted
       were  originally  at  the  end  of the buffer, the current line number shall be set to the
       address of the new last line; if no lines remain in the buffer, the  current  line  number
       shall be set to zero.

   Edit Command
       Synopsis:

	      e [file]

       The  e  command	shall  delete the entire contents of the buffer and then read in the file
       named by the pathname file.  The current line number shall be set to the  address  of  the
       last  line  of  the buffer. If no pathname is given, the currently remembered pathname, if
       any, shall be used (see the f command).	The number of bytes  read  shall  be  written  to
       standard output, unless the -s option was specified, in the following format:

	      "%d\n", <number of bytes read>

       The  name file shall be remembered for possible use as a default pathname in subsequent e,
       E, r, and w commands. If file is replaced by '!' , the rest of the line shall be taken  to
       be a shell command line whose output is to be read. Such a shell command line shall not be
       remembered as the current file. All marks shall be discarded upon the completion of a suc-
       cessful	e  command.  If  the buffer has changed since the last time the entire buffer was
       written, the user shall be warned, as described previously.

   Edit Without Checking Command
       Synopsis:

	      E [file]

       The E command shall possess all properties and restrictions of the e command  except  that
       the  editor  shall not check to see whether any changes have been made to the buffer since
       the last w command.

   Filename Command
       Synopsis:

	      f [file]

       If file is given, the f command shall change the currently remembered  pathname	to  file;
       whether	the  name  is  changed	or  not, it shall then write the (possibly new) currently
       remembered pathname to the standard output in the following format:

	      "%s\n", <pathname>

       The current line number shall be unchanged.

   Global Command
       Synopsis:

	      (1,$)g/RE/command list

       In the g command, the first step shall be to mark every line for which the line	excluding
       the  terminating  <newline> matches the given RE. Then, going sequentially from the begin-
       ning of the file to the end of the file, the given command list shall be executed for each
       marked  line, with the current line number set to the address of that line. Any line modi-
       fied by the command list shall be unmarked. When the g command completes, the current line
       number  shall  have  the  value assigned by the last command in the command list. If there
       were no matching lines, the current line number shall not be changed. A single command  or
       the  first  of a list of commands shall appear on the same line as the global command. All
       lines of a multi-line list except the last line shall be ended with a backslash	preceding
       the  terminating  <newline>;  the a, i, and c commands and associated input are permitted.
       The '.'	terminating input mode can be omitted if it would be the last line of the command
       list.  An empty command list shall be equivalent to the p command. The use of the g, G, v,
       V, and ! commands in the command list produces undefined results. Any character other than
       <space>	or <newline> can be used instead of a slash to delimit the RE. Within the RE, the
       RE delimiter itself can be used as a literal character if it is preceded by a backslash.

   Interactive Global Command
       Synopsis:

	      (1,$)G/RE/

       In the G command, the first step shall be to mark every line for which the line	excluding
       the terminating <newline> matches the given RE. Then, for every such line, that line shall
       be written, the current line number shall be set to the address of that line, and any  one
       command	(other	than  one of the a, c, i, g, G, v, and V commands) shall be read and exe-
       cuted. A <newline> shall act as a null command (causing no action to be taken on the  cur-
       rent  line);  an '&' shall cause the re-execution of the most recent non-null command exe-
       cuted within the current invocation of G. Note that the commands input as part of the exe-
       cution  of the G command can address and affect any lines in the buffer. Any line modified
       by the command shall be unmarked. The final value of the current line number shall be  the
       value  set by the last command successfully executed. (Note that the last command success-
       fully executed shall be the G command itself if a command fails or  the	null  command  is
       specified.) If there were no matching lines, the current line number shall not be changed.
       The G command can be terminated by a SIGINT signal. Any character other	than  <space>  or
       <newline> can be used instead of a slash to delimit the RE and the replacement. Within the
       RE, the RE delimiter itself can be used as a literal character if  it  is  preceded  by	a
       backslash.

   Help Command
       Synopsis:

	      h

       The  h command shall write a short message to standard output that explains the reason for
       the most recent '?'  notification. The current line number shall be unchanged.

   Help-Mode Command
       Synopsis:

	      H

       The H command shall cause ed to enter a mode in which help messages (see  the  h  command)
       shall  be  written  to standard output for all subsequent '?' notifications. The H command
       alternately shall turn this mode on and off; it is initially  off.  If  the  help-mode  is
       being  turned  on, the H command also explains the previous '?' notification, if there was
       one. The current line number shall be unchanged.

   Insert Command
       Synopsis:

	      (.)i
	      <text>
	      .

       The i command shall insert the given text before the addressed line; the current  line  is
       set  to	the last inserted line or, if there was none, to the addressed line. This command
       differs from the a command only in the placement of the input text.  Address  0	shall  be
       valid for this command; it shall be interpreted as if address 1 were specified.

   Join Command
       Synopsis:

	      (.,.+1)j

       The  j  command	shall  join  contiguous  lines by removing the appropriate <newline>s. If
       exactly one address is given, this command shall do nothing. If lines are joined, the cur-
       rent  line  number  shall be set to the address of the joined line; otherwise, the current
       line number shall be unchanged.

   Mark Command
       Synopsis:

	      (.)kx

       The k command shall mark the addressed line with  name  x,  which  the  application  shall
       ensure  is a lowercase letter from the portable character set. The address "'x" shall then
       refer to this line; the current line number shall be unchanged.

   List Command
       Synopsis:

	      (.,.)l

       The l command shall write to standard output the addressed lines in a visually unambiguous
       form.  The characters listed in the Base Definitions volume of IEEE Std 1003.1-2001, Table
       5-1, Escape Sequences and Associated Actions ( '\\' , '\a' , '\b' , '\f' , '\r' ,  '\t'	,
       '\v'  )	shall  be written as the corresponding escape sequence; the '\n' in that table is
       not applicable. Non-printable characters not in the table shall be written as  one  three-
       digit  octal  number (with a preceding backslash character) for each byte in the character
       (most significant byte first). If the size of a byte on the system is  greater  than  nine
       bits, the format used for non-printable characters is implementation-defined.

       Long lines shall be folded, with the point of folding indicated by <newline> preceded by a
       backslash; the length at which folding occurs is unspecified, but  should  be  appropriate
       for  the  output device. The end of each line shall be marked with a '$' , and '$' charac-
       ters within the text shall be written with a preceding backslash.  An  l  command  can  be
       appended  to any other command other than e, E, f, q, Q, r, w, or !. The current line num-
       ber shall be set to the address of the last line written.

   Move Command
       Synopsis:

	      (.,.)maddress

       The m command shall reposition the addressed lines after the line  addressed  by  address.
       Address	0  shall  be  valid  for address and cause the addressed lines to be moved to the
       beginning of the buffer. It shall be an error if address address falls within the range of
       moved lines. The current line number shall be set to the address of the last line moved.

   Number Command
       Synopsis:

	      (.,.)n

       The  n  command shall write to standard output the addressed lines, preceding each line by
       its line number and a <tab>; the current line number shall be set to the  address  of  the
       last  line written. The n command can be appended to any command other than e, E, f, q, Q,
       r, w, or !.

   Print Command
       Synopsis:

	      (.,.)p

       The p command shall write to standard output the addressed lines; the current line  number
       shall be set to the address of the last line written. The p command can be appended to any
       command other than e, E, f, q, Q, r, w, or !.

   Prompt Command
       Synopsis:

	      P

       The P command shall cause ed to prompt with an asterisk ( '*' ) (or string, if -p is spec-
       ified)  for  all  subsequent commands. The P command alternatively shall turn this mode on
       and off; it shall be initially on if the -p option is specified; otherwise, off. The  cur-
       rent line number shall be unchanged.

   Quit Command
       Synopsis:

	      q

       The  q  command	shall cause ed to exit. If the buffer has changed since the last time the
       entire buffer was written, the user shall be warned, as described previously.

   Quit Without Checking Command
       Synopsis:

	      Q

       The Q command shall cause ed to exit without checking whether changes have  been  made  in
       the buffer since the last w command.

   Read Command
       Synopsis:

	      ($)r [file]

       The  r  command	shall read in the file named by the pathname file and append it after the
       addressed line. If no file argument is given, the currently remembered pathname,  if  any,
       shall  be used (see the e and f commands).  The currently remembered pathname shall not be
       changed unless there is no remembered pathname. Address 0 shall be valid for r  and  shall
       cause  the  file to be read at the beginning of the buffer. If the read is successful, and
       -s was not specified, the number of bytes read shall be written to standard output in  the
       following format:

	      "%d\n", <number of bytes read>

       The  current  line number shall be set to the address of the last line read in. If file is
       replaced by '!' , the rest of the line shall be taken to be a  shell  command  line  whose
       output  is  to  be  read. Such a shell command line shall not be remembered as the current
       pathname.

   Substitute Command
       Synopsis:

	      (.,.)s/RE/replacement/flags

       The s command shall search each addressed line for an occurrence of the specified  RE  and
       replace either the first or all (non-overlapped) matched strings with the replacement; see
       the following description of the g suffix. It is an error if  the  substitution	fails  on
       every addressed line. Any character other than <space> or <newline> can be used instead of
       a slash to delimit the RE and the replacement. Within the RE, the RE delimiter itself  can
       be used as a literal character if it is preceded by a backslash. The current line shall be
       set to the address of the last line on which a substitution occurred.

       An ampersand ( '&' ) appearing in the replacement shall be replaced by the string matching
       the  RE	on the current line. The special meaning of '&' in this context can be suppressed
       by preceding it by backslash. As a more general feature, the characters '\n' , where n  is
       a digit, shall be replaced by the text matched by the corresponding back-reference expres-
       sion. When the character '%' is the only character in  the  replacement,  the  replacement
       used in the most recent substitute command shall be used as the replacement in the current
       substitute command; if there was no previous substitute command, the use of  '%'  in  this
       manner  shall be an error. The '%' shall lose its special meaning when it is in a replace-
       ment string of more than one character or is preceded by a backslash. For each backslash (
       '\'  )  encountered in scanning replacement from beginning to end, the following character
       shall lose its special meaning (if any). It is unspecified what special meaning	is  given
       to any character other than '&' , '\' , '%' , or digits.

       A  line	can be split by substituting a <newline> into it. The application shall ensure it
       escapes the <newline> in the replacement by preceding it by backslash.  Such  substitution
       cannot  be  done as part of a g or v command list. The current line number shall be set to
       the address of the last line on which a substitution is performed. If no  substitution  is
       performed, the current line number shall be unchanged.  If a line is split, a substitution
       shall be considered to have been performed on each of the new lines  for  the  purpose  of
       determining  the  new current line number. A substitution shall be considered to have been
       performed even if the replacement string is identical to the string that it replaces.

       The application shall ensure that the value of flags is zero or more of:

       count  Substitute for the countth occurrence only of the RE found on each addressed line.

       g      Globally substitute for all non-overlapping instances of the RE  rather  than  just
	      the first one. If both g and count are specified, the results are unspecified.

       l      Write  to standard output the final line in which a substitution was made. The line
	      shall be written in the format specified for the l command.

       n      Write to standard output the final line in which a substitution was made. The  line
	      shall be written in the format specified for the n command.

       p      Write  to standard output the final line in which a substitution was made. The line
	      shall be written in the format specified for the p command.

   Copy Command
       Synopsis:

	      (.,.)taddress

       The t command shall be equivalent to the m command, except that a copy  of  the	addressed
       lines  shall  be  placed  after	address address (which can be 0); the current line number
       shall be set to the address of the last line added.

   Undo Command
       Synopsis:

	      u

       The u command shall nullify the effect of the most recent command that  modified  anything
       in the buffer, namely the most recent a, c, d, g, i, j, m, r, s, t, u, v, G, or V command.
       All changes made to the buffer by a g, G, v, or V global command shall be undone as a sin-
       gle  change;  if  no changes were made by the global command (such as with g/RE/ p), the u
       command shall have no effect. The current line number shall be set to  the  value  it  had
       immediately before the command being undone started.

   Global Non-Matched Command
       Synopsis:

	      (1,$)v/RE/command list

       This  command  shall  be equivalent to the global command g except that the lines that are
       marked during the first step shall be those for which the line excluding  the  terminating
       <newline> does not match the RE.

   Interactive Global Not-Matched Command
       Synopsis:

	      (1,$)V/RE/

       This command shall be equivalent to the interactive global command G except that the lines
       that are marked during the first step shall be those for which the line excluding the ter-
       minating <newline> does not match the RE.

   Write Command
       Synopsis:

	      (1,$)w [file]

       The  w  command	shall write the addressed lines into the file named by the pathname file.
       The command shall create the file, if it does not exist, or shall replace the contents  of
       the  existing file. The currently remembered pathname shall not be changed unless there is
       no remembered pathname. If no pathname is given, the  currently	remembered  pathname,  if
       any, shall be used (see the e and f commands); the current line number shall be unchanged.
       If the command is successful, the number of bytes written shall	be  written  to  standard
       output, unless the -s option was specified, in the following format:

	      "%d\n", <number of bytes written>

       If  file  begins with '!' , the rest of the line shall be taken to be a shell command line
       whose standard input shall be the addressed lines. Such a shell command line shall not  be
       remembered  as the current pathname. This usage of the write command with '!' shall not be
       considered as a "last w command that wrote the entire buffer",  as  described  previously;
       thus,  this  alone  shall  not  prevent	the  warning to the user if an attempt is made to
       destroy the editor buffer via the e or q commands.

   Line Number Command
       Synopsis:

	      ($)=

       The line number of the addressed line shall be written to standard output in the following
       format:

	      "%d\n", <line number>

       The current line number shall be unchanged by this command.

   Shell Escape Command
       Synopsis:

	      !command

       The  remainder  of  the	line after the '!' shall be sent to the command interpreter to be
       interpreted as a shell command line. Within the text  of  that  shell  command  line,  the
       unescaped  character  '%' shall be replaced with the remembered pathname; if a '!' appears
       as the first character of the command, it shall be replaced with the text of the  previous
       shell  command  executed  via  '!' . Thus, "!!" shall repeat the previous !command. If any
       replacements of '%' or '!' are performed, the modified line shall be written to the  stan-
       dard output before command is executed. The ! command shall write:

	      "!\n"

       to  standard  output  upon completion, unless the -s option is specified. The current line
       number shall be unchanged.

   Null Command
       Synopsis:

	      (.+1)

       An address alone on a line shall cause the addressed line  to  be  written.   A	<newline>
       alone  shall  be equivalent to "+1p" . The current line number shall be set to the address
       of the written line.

EXIT STATUS
       The following exit values shall be returned:

	0     Successful completion without any file or command errors.

       >0     An error occurred.

CONSEQUENCES OF ERRORS
       When an error in the input script is encountered, or when an error is detected that  is	a
       consequence  of the data (not) present in the file or due to an external condition such as
       a read or write error:

	* If the standard input is a terminal device file, all input shall be flushed, and a  new
	  command read.

	* If  the  standard input is a regular file, ed shall terminate with a non-zero exit sta-
	  tus.

       The following sections are informative.

APPLICATION USAGE
       Because of the extremely terse nature of the default error messages,  the  prudent  script
       writer  begins  the ed input commands with an H command, so that if any errors do occur at
       least some clue as to the cause is made available.

       In previous versions, an obsolescent - option was described.  This is no longer specified.
       Applications  should use the -s option. Using - as a file operand now produces unspecified
       results. This allows implementations to continue to support the former required behavior.

EXAMPLES
       None.

RATIONALE
       The initial description of this utility was adapted from the SVID.  It contains some  fea-
       tures  not  found in Version 7 or BSD-derived systems. Some of the differences between the
       POSIX and BSD ed utilities include, but need not be limited to:

	* The BSD - option does not suppress the '!' prompt after a ! command.

	* BSD does not support the special meanings of the '%' and '!'	 characters  within  a	!
	  command.

	* BSD does not support the addresses ';' and ',' .

	* BSD  allows  the  command/suffix pairs pp, ll, and so on, which are unspecified in this
	  volume of IEEE Std 1003.1-2001.

	* BSD does not support the '!' character part of the e, r, or w commands.

	* A failed g command in BSD sets the line number to the last line searched if  there  are
	  no matches.

	* BSD does not default the command list to the p command.

	* BSD does not support the G, h, H, n, or V commands.

	* On  BSD,  if	there is no inserted text, the insert command changes the current line to
	  the referenced line -1; that is, the line before the specified line.

	* On BSD, the join command with only a single address changes the current  line  to  that
	  address.

	* BSD  does  not support the P command; moreover, in BSD it is synonymous with the p com-
	  mand.

	* BSD does not support the undo of the commands j, m, r, s, or t.

	* The Version 7 ed command W, and the BSD ed commands W, wq, and z  are  not  present  in
	  this volume of IEEE Std 1003.1-2001.

       The -s option was added to allow the functionality of the now withdrawn - option in a man-
       ner compatible with the Utility Syntax Guidelines.

       In early proposals there was a limit, {ED_FILE_MAX}, that described the historical limita-
       tions  of some ed utilities in their handling of large files; some of these have had prob-
       lems with files larger than 100000 bytes. It was this limitation that prompted much of the
       desire to include a split command in this volume of IEEE Std 1003.1-2001. Since this limit
       was removed, this volume of IEEE Std 1003.1-2001 requires  that	implementations  document
       the  file  size	limits imposed by ed in the conformance document. The limit {ED_LINE_MAX}
       was also removed; therefore, the global limit {LINE_MAX} is  used  for  input  and  output
       lines.

       The manner in which the l command writes non-printable characters was changed to avoid the
       historical backspace-overstrike method. On video  display  terminals,  the  overstrike  is
       ambiguous because most terminals simply replace overstruck characters, making the l format
       not useful for its intended purpose of unambiguously  understanding  the  content  of  the
       line.  The  historical  backslash  escapes were also ambiguous. (The string "a\0011" could
       represent a line containing those six characters or a line containing the three characters
       'a'  , a byte with a binary value of 1, and a 1.) In the format required here, a backslash
       appearing in the line is written as "\\" so that the  output  is  truly	unambiguous.  The
       method of marking the ends of lines was adopted from the ex editor and is required for any
       line ending in <space>s; the '$' is placed on all lines so that a real '$' at the end of a
       line cannot be misinterpreted.

       Systems	with  bytes  too  large to fit into three octal digits must devise other means of
       displaying non-printable characters.  Consideration was given to requiring that the number
       of  octal  digits  be large enough to hold a byte, but this seemed to be too confusing for
       applications on the vast majority of systems where three digits are adequate. It would  be
       theoretically  possible	for  the  application  to use the getconf utility to find out the
       CHAR_BIT value and deal with such an algorithm; however, there is really no  portable  way
       that  an  application can use the octal values of the bytes across various coded character
       sets, so the additional specification was not worthwhile.

       The description of how a NUL is written was removed. The NUL character cannot be  in  text
       files,  and this volume of IEEE Std 1003.1-2001 should not dictate behavior in the case of
       undefined, erroneous input.

       Unlike some of the other editing utilities, the filenames accepted by the E, e, R,  and	r
       commands are not patterns.

       Early  proposals  stated that the -p option worked only when standard input was associated
       with a terminal device. This has been changed to conform  to  historical  implementations,
       thereby allowing applications to interpose themselves between a user and the ed utility.

       The  form  of the substitute command that uses the n suffix was limited in some historical
       documentation (where this was described incorrectly as "backreferencing"). This limit  has
       been  omitted  because  there  is  no  reason why an editor processing lines of {LINE_MAX}
       length should have this restriction. The command s/x/X/2047 should be able  to  substitute
       the 2047th occurrence of 'x' on a line.

       The  use  of printing commands with printing suffixes (such as pn, lp, and so on) was made
       unspecified because BSD-based systems allow this, whereas System V does not.

       Some BSD-based systems exit immediately upon receipt of end-of-file if all of the lines in
       the file have been deleted. Since this volume of IEEE Std 1003.1-2001 refers to the q com-
       mand in this instance, such behavior is not allowed.

       Some historical implementations returned exit status  zero  even  if  command  errors  had
       occurred; this is not allowed by this volume of IEEE Std 1003.1-2001.

       Some historical implementations contained a bug that allowed a single period to be entered
       in input mode as <backslash> <period> <newline>. This is not allowed by ed  because  there
       is no description of escaping any of the characters in input mode; backslashes are entered
       into the buffer exactly as typed. The typical method of entering a single period has  been
       to  precede  it	with another character and then use the substitute command to delete that
       character.

       It is difficult under some modes of some versions of historical operating system  terminal
       drivers	 to  distinguish  between  an  end-of-file  condition  and  terminal  disconnect.
       IEEE Std 1003.1-2001 does not require implementations to distinguish between the two situ-
       ations, which permits historical implementations of the ed utility on historical platforms
       to conform.  Implementations are encouraged to distinguish between the two,  if	possible,
       and take appropriate action on terminal disconnect.

       Historically,  ed accepted a zero address for the a and r commands in order to insert text
       at the start of the edit buffer. When the buffer was empty the command .=  returned  zero.
       IEEE Std 1003.1-2001 requires conformance to historical practice.

       For  consistency with the a and r commands and better user functionality, the i and c com-
       mands must also accept an address of 0, in which case 0i is treated as 1i and likewise for
       the c command.

       All of the following are valid addresses:

       +++    Three lines after the current line.

       /pattern/-
	      One line before the next occurrence of pattern.

       -2     Two lines before the current line.

       3 ---- 2
	      Line one (note the intermediate negative address).

       1 2 3  Line six.

       Any  number  of	addresses  can	be  provided  to  commands taking addresses; for example,
       "1,2,3,4,5p" prints lines 4 and 5, because two is the greatest valid number  of	addresses
       accepted  by the print command. This, in combination with the semicolon delimiter, permits
       users to create commands based on ordered patterns in the file. For example,  the  command
       "3;/foo/;+2p" will display the first line after line 3 that contains the pattern foo, plus
       the next two lines. Note that the address "3;" must still be evaluated before  being  dis-
       carded, because the search origin for the "/foo/" command depends on this.

       Historically, ed disallowed address chains, as discussed above, consisting solely of comma
       or semicolon separators; for example, ",,," or ";;;" were considered an error. For consis-
       tency  of  address  specification,  this restriction is removed. The following table lists
       some of the address forms now possible:

			Address  Addr1	Addr2  Status	   Comment
			7,	 7	7      Historical
			7,5,	 5	5      Historical
			7,5,9	 5	9      Historical
			7,9	 7	9      Historical
			7,+	 7	8      Historical
			,	 1	$      Historical
			,7	 1	7      Extension
			,,	 $	$      Extension
			,;	 $	$      Extension
			7;	 7	7      Historical
			7;5;	 5	5      Historical
			7;5;9	 5	9      Historical
			7;5,9	 5	9      Historical
			7;$;4	 $	4      Historical  Valid, but erroneous.
			7;9	 7	9      Historical
			7;+	 7	8      Historical
			;	 .	$      Historical
			;7	 .	7      Extension
			;;	 $	$      Extension
			;,	 $	$      Extension

       Historically, values could be added to addresses by  including  them  after  one  or  more
       <blank>s;  for example, "3 - 5p" wrote the seventh line of the file, and "/foo/ 5" was the
       same as "5 /foo/" . However, only absolute values could be added; for  example,	"5 /foo/"
       was an error. IEEE Std 1003.1-2001 requires conformance to historical practice.

       Historically,  ed accepted the '^' character as an address, in which case it was identical
       to the hyphen character. IEEE Std 1003.1-2001 does not require or prohibit this behavior.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Utility Description Defaults , ex , sed , sh , vi

COPYRIGHT
       Portions of this text are reprinted and	reproduced  in	electronic  form  from	IEEE  Std
       1003.1,	2003  Edition,	Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003					    ED(P)


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