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Plan 9 - man page for sed (plan9 section 1)

SED(1)				     General Commands Manual				   SED(1)

NAME
       sed - stream editor

SYNOPSIS
       sed [ -n ] [ -g ] [ -e script ] [ -f sfile ] [ file ...	]

DESCRIPTION
       Sed copies the named files (standard input default) to the standard output, edited accord-
       ing to a script of commands.  The -f option causes the script to be taken from file sfile;
       these  options accumulate.  If there is just one -e option and no -f's, the flag -e may be
       omitted.  The -n option suppresses the default output; -g causes all substitutions  to  be
       global, as if suffixed g.

       A script consists of editing commands, one per line, of the following form:

	      [address [, address] ] function [argument ...]

       In  normal  operation  sed  cyclically copies a line of input into a pattern space (unless
       there is something left after a command), applies in sequence all commands whose addresses
       select  that  pattern  space, and at the end of the script copies the pattern space to the
       standard output (except under -n) and deletes the pattern space.

       An address is either a decimal number that counts input lines cumulatively across files, a
       that  addresses the last line of input, or a context address, /regular-expression/, in the
       style of regexp(6), with the added convention that matches a newline embedded in the  pat-
       tern space.

       A command line with no addresses selects every pattern space.

       A command line with one address selects each pattern space that matches the address.

       A command line with two addresses selects the inclusive range from the first pattern space
       that matches the first address through the next pattern space  that  matches  the  second.
       (If  the  second address is a number less than or equal to the line number first selected,
       only one line is selected.)  Thereafter the process is repeated,  looking  again  for  the
       first address.

       Editing	commands  can  be  applied  to non-selected pattern spaces by use of the negation
       function (below).

       An argument denoted text consists of one or more lines, all but the last of which end with
       to  hide the newline.  Backslashes in text are treated like backslashes in the replacement
       string of an command, and may be used to protect  initial  blanks  and  tabs  against  the
       stripping that is done on every script line.

       An argument denoted rfile or wfile must terminate the command line and must be preceded by
       exactly one blank.  Each wfile is created before processing begins.  There can be at  most
       120 distinct wfile arguments.

       a\
       text	    Append.  Place text on the output before reading the next input line.

       b label	    Branch  to the : command bearing the label.  If label is empty, branch to the
		    end of the script.

       c\
       text	    Change.  Delete the pattern space.	With 0 or 1 address or at the  end  of	a
		    2-address range, place text on the output.	Start the next cycle.

       d	    Delete the pattern space.  Start the next cycle.

       D	    Delete  the  initial  segment of the pattern space through the first newline.
		    Start the next cycle.

       g	    Replace the contents of the pattern space by the contents of the hold space.

       G	    Append the contents of the hold space to the pattern space.

       h	    Replace the contents of the hold space by the contents of the pattern space.

       H	    Append the contents of the pattern space to the hold space.

       i\
       text	    Insert.  Place text on the standard output.

       n	    Copy the pattern space to the standard output.   Replace  the  pattern  space
		    with the next line of input.

       N	    Append  the next line of input to the pattern space with an embedded newline.
		    (The current line number changes.)

       p	    Print.  Copy the pattern space to the standard output.

       P	    Copy the initial segment of the pattern space through the  first  newline  to
		    the standard output.

       q	    Quit.  Branch to the end of the script.  Do not start a new cycle.

       r rfile	    Read the contents of rfile.  Place them on the output before reading the next
		    input line.

       s/regular-expression/replacement/flags
		    Substitute the replacement string for instances of the regular-expression  in
		    the  pattern  space.   Any	character  may	be  used  instead of For a fuller
		    description see regexp(6).	Flags is zero or more of

		    g	   Global.  Substitute for all non-overlapping instances of  the  regular
			   expression rather than just the first one.

		    p	   Print the pattern space if a replacement was made.

		    w wfile
			   Write.  Append the pattern space to wfile if a replacement was made.

       t label	    Test.  Branch to the command bearing the label if any substitutions have been
		    made since the most recent reading of an input line  or  execution	of  a  If
		    label is empty, branch to the end of the script.

       w	    wfile
		    Write.  Append the pattern space to wfile.

       x	    Exchange the contents of the pattern and hold spaces.

       y/string1/string2/
		    Transform.	 Replace all occurrences of characters in string1 with the corre-
		    sponding character in string2.  The lengths of string1 and	string2  must  be
		    equal.

       !function    Don't.   Apply  the  function  (or	group,	if  function is only to lines not
		    selected by the address(es).

       : label	    This command does nothing; it bears a label for b and t  commands  to  branch
		    to.

       =	    Place the current line number on the standard output as a line.

       {	    Execute the following commands through a matching only when the pattern space
		    is selected.

		    An empty command is ignored.

EXAMPLES
       sed 10q file
	      Print the first 10 lines of the file.

       sed '/^$/d'
	      Delete empty lines from standard input.

       sed 's/UNIX/& system/g'
	      Replace every instance of by

       sed 's/ *$//   drop trailing blanks
       /^$/d		   drop empty lines
       s/  */\	      replace blanks by newlines
       /g
       /^$/d' chapter*
	      Print the files chapter1, chapter2, etc. one word to a line.

       nroff -ms manuscript | sed '
       ${
	    /^$/p	   if last line of file is empty, print it
       }
       //N	      if current line is empty, append next line
       /^\n$/D'       if two lines are empty, delete the first
	      Delete all but one of each group of empty lines from a formatted manuscript.

SOURCE
       /sys/src/cmd/sed.c

SEE ALSO
       ed(1), grep(1), awk(1), lex(1), sam(1), regexp(6)
       L. E. McMahon, `SED -- A Non-interactive Text Editor', Unix Research  System  Programmer's
       Manual, Volume 2.

BUGS
       If input is from a pipe, buffering may consume characters beyond a line on which a command
       is executed.

											   SED(1)


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