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OpenDarwin 7.2.1 - man page for sed (opendarwin section 1)

SED(1)				   BSD General Commands Manual				   SED(1)

NAME
     sed -- stream editor

SYNOPSIS
     sed [-an] command [file ...]
      [-an] [-e command] [-f command_file] [file ...]

DESCRIPTION
     The sed utility reads the specified files, or the standard input if no files are specified,
     modifying the input as specified by a list of commands.  The input is then written to the
     standard output.

     A single command may be specified as the first argument to .  Multiple commands may be spec-
     ified by using the -e or -f options.  All commands are applied to the input in the order
     they are specified regardless of their origin.

     The following options are available:

     -a      The files listed as parameters for the ``w'' functions are created (or truncated)
	     before any processing begins, by default.	The -a option causes sed to delay opening
	     each file until a command containing the related ``w'' function is applied to a line
	     of input.

     -e command
	     Append the editing commands specified by the command argument to the list of com-
	     mands.

     -f command_file
	     Append the editing commands found in the file command_file to the list of commands.
	     The editing commands should each be listed on a separate line.

     -n      By default, each line of input is echoed to the standard output after all of the
	     commands have been applied to it.	The -n option suppresses this behavior.

     The form of a sed command is as follows:

	   [address[,address]]function[arguments]

     Whitespace may be inserted before the first address and the function portions of the com-
     mand.

     Normally, sed cyclically copies a line of input, not including its terminating newline char-
     acter, into a pattern space, (unless there is something left after a ``D'' function),
     applies all of the commands with addresses that select that pattern space, copies the pat-
     tern space to the standard output, appending a newline, and deletes the pattern space.

     Some of the functions use a hold space to save all or part of the pattern space for subse-
     quent retrieval.

Sed Addresses
     An address is not required, but if specified must be a number (that counts input lines cumu-
     latively across input files), a dollar (``$'') character that addresses the last line of
     input, or a context address (which consists of a regular expression preceded and followed by
     a delimiter).

     A command line with no addresses selects every pattern space.

     A command line with one address selects all of the pattern spaces that match 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
     that line is selected.)  Starting at the first line following the selected range, sed starts
     looking again for the first address.

     Editing commands can be applied to non-selected pattern spaces by use of the exclamation
     character (``''!)	function.

Sed Regular Expressions
     The sed regular expressions are basic regular expressions (BRE's, see regex(3) for more
     information).  In addition, sed has the following two additions to BRE's:

     1.   In a context address, any character other than a backslash (``\'') or newline character
	  may be used to delimit the regular expression by prefixing the first use of that delim-
	  iter with a backslash.  Also, putting a backslash character before the delimiting char-
	  acter causes the character to be treated literally.  For example, in the context
	  address \xabc\xdefx, the RE delimiter is an ``x'' and the second ``x'' stands for
	  itself, so that the regular expression is ``abcxdef''.

     2.   The escape sequence \n matches a newline character embedded in the pattern space.  You
	  can't, however, use a literal newline character in an address or in the substitute com-
	  mand.

     One special feature of sed regular expressions is that they can default to the last regular
     expression used.  If a regular expression is empty, i.e. just the delimiter characters are
     specified, the last regular expression encountered is used instead.  The last regular
     expression is defined as the last regular expression used as part of an address or substi-
     tute command, and at run-time, not compile-time.  For example, the command ``/abc/s//XXX/''
     will substitute ``XXX'' for the pattern ``abc''.

Sed Functions
     In the following list of commands, the maximum number of permissible addresses for each com-
     mand is indicated by [0addr], [1addr], or [2addr], representing zero, one, or two addresses.

     The argument text consists of one or more lines.  To embed a newline in the text, precede it
     with a backslash.	Other backslashes in text are deleted and the following character taken
     literally.

     The ``r'' and ``w'' functions take an optional file parameter, which should be separated
     from the function letter by white space.  Each file given as an argument to sed is created
     (or its contents truncated) before any input processing begins.

     The ``b'', ``r'', ``s'', ``t'', ``w'', ``y'', ``''!, and ``:'' functions all accept addi-
     tional arguments.	The following synopses indicate which arguments have to be separated from
     the function letters by white space characters.

     Two of the functions take a function-list.  This is a list of sed functions separated by
     newlines, as follows:

	   { function
	     function
	     ...
	     function
	   }

     The ``{'' can be preceded by white space and can be followed by white space.  The function
     can be preceded by white space.  The terminating ``}'' must be preceded by a newline or
     optional white space.

     [2addr] function-list
	     Execute function-list only when the pattern space is selected.

     [1addr]a\
     text
	     Write text to standard output immediately before each attempt to read a line of
	     input, whether by executing the ``N'' function or by beginning a new cycle.

     [2addr]b[label]
	     Branch to the ``:'' function with the specified label.  If the label is not speci-
	     fied, branch to the end of the script.

     [2addr]c\
     text
	     Delete the pattern space.	With 0 or 1 address or at the end of a 2-address range,
	     text is written to the standard output.

     [2addr]d
	     Delete the pattern space and start the next cycle.

     [2addr]D
	     Delete the initial segment of the pattern space through the first newline character
	     and start the next cycle.

     [2addr]g
	     Replace the contents of the pattern space with the contents of the hold space.

     [2addr]G
	     Append a newline character followed by the contents of the hold space to the pattern
	     space.

     [2addr]h
	     Replace the contents of the hold space with the contents of the pattern space.

     [2addr]H
	     Append a newline character followed by the contents of the pattern space to the hold
	     space.

     [1addr]i\
     text
	     Write text to the standard output.

     [2addr]l
	     (The letter ell.)	Write the pattern space to the standard output in a visually
	     unambiguous form.	This form is as follows:

		   backslash	      \\
		   alert	      \a
		   form-feed	      \f
		   newline	      \n
		   carriage-return    \r
		   tab		      \t
		   vertical tab       \v

	     Nonprintable characters are written as three-digit octal numbers (with a preceding
	     backslash) for each byte in the character (most significant byte first).  Long lines
	     are folded, with the point of folding indicated by displaying a backslash followed
	     by a newline.  The end of each line is marked with a ``$''.

     [2addr]n
	     Write the pattern space to the standard output if the default output has not been
	     suppressed, and replace the pattern space with the next line of input.

     [2addr]N
	     Append the next line of input to the pattern space, using an embedded newline char-
	     acter to separate the appended material from the original contents.  Note that the
	     current line number changes.

     [2addr]p
	     Write the pattern space to standard output.

     [2addr]P
	     Write the pattern space, up to the first newline character to the standard output.

     [1addr]q
	     Branch to the end of the script and quit without starting a new cycle.

     [1addr]r file
	     Copy the contents of file to the standard output immediately before the next attempt
	     to read a line of input.  If file cannot be read for any reason, it is silently
	     ignored and no error condition is set.

     [2addr]s/regular expression/replacement/flags
	     Substitute the replacement string for the first instance of the regular expression
	     in the pattern space.  Any character other than backslash or newline can be used
	     instead of a slash to delimit the RE and the replacement.	Within the RE and the
	     replacement, the RE delimiter itself can be used as a literal character if it is
	     preceded by a backslash.

	     An ampersand (``&'') appearing in the replacement is replaced by the string matching
	     the RE.  The special meaning of ``&'' in this context can be suppressed by preceding
	     it by a backslash.  The string ``\#'', where ``#'' is a digit, is replaced by the
	     text matched by the corresponding backreference expression (see re_format(7) ).

	     A line can be split by substituting a newline character into it.  To specify a new-
	     line character in the replacement string, precede it with a backslash.

	     The value of flags in the substitute function is zero or more of the following:

		   0 ... 9
			   Make the substitution only for the N'th occurrence of the regular
			   expression in the pattern space.

		   g	   Make the substitution for all non-overlapping matches of the regular
			   expression, not just the first one.

		   p	   Write the pattern space to standard output if a replacement was made.
			   If the replacement string is identical to that which it replaces, it
			   is still considered to have been a replacement.

		   w file  Append the pattern space to file if a replacement was made.	If the
			   replacement string is identical to that which it replaces, it is still
			   considered to have been a replacement.

     [2addr]t [label]
	     Branch to the ``'': function bearing the label if any substitutions have been made
	     since the most recent reading of an input line or execution of a ``t'' function.  If
	     no label is specified, branch to the end of the script.

     [2addr]w file
	     Append the pattern space to the file.

     [2addr]x
	     Swap the contents of the pattern and hold spaces.

     [2addr]y/string1/string2/
	     Replace all occurrences of characters in string1 in the pattern space with the cor-
	     responding characters from string2.  Any character other than a backslash or newline
	     can be used instead of a slash to delimit the strings.  Within string1 and string2,
	     a backslash followed by any character other than a newline is that literal charac-
	     ter, and a backslash followed by an ``n'' is replaced by a newline character.

     [2addr]!function
     [2addr]!function-list
	     Apply the function or function-list only to the lines that are not selected by the
	     address(es).

     [0addr]:label
	     This function does nothing; it bears a label to which the ``b'' and ``t'' commands
	     may branch.

     [1addr]=
	     Write the line number to the standard output followed by a newline character.

     [0addr]
	     Empty lines are ignored.

     [0addr]#
	     The ``#'' and the remainder of the line are ignored (treated as a comment), with the
	     single exception that if the first two characters in the file are ``#n'', the
	     default output is suppressed.  This is the same as specifying the -n option on the
	     command line.

     The sed utility exits 0 on success and >0 if an error occurs.

SEE ALSO
     awk(1), ed(1), grep(1), regex(3), re_format(7)

STANDARDS
     The sed function is expected to be a superset of the IEEE Std 1003.2 (``POSIX.2'') specifi-
     cation.

HISTORY
     A sed command appeared in Version 7 AT&T UNIX.

BSD					December 30, 1993				      BSD


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