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

NAME
     sed — stream editor

SYNOPSIS
     sed [-Ealnr] command [file ...]
     sed [-Ealnr] [-e command] [-f command_file] [-I extension] [-i extension]
	 [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 com‐
     mands.  The input is then written to the standard output.

     A single command may be specified as the first argument to sed.  Multiple
     commands may be specified 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:

     -E	     Interpret regular expressions as extended (modern) regular
	     expressions rather than basic regular expressions (BRE's).	 The
	     re_format(7) manual page fully describes both formats.

     -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 con‐
	     taining 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 commands.

     -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.

     -I extension
	     Edit files in-place, saving backups with the specified extension.
	     If a zero-length extension is given, no backup will be saved.  It
	     is not recommended to give a zero-length extension when in-place
	     editing files, as you risk corruption or partial content in situ‐
	     ations where disk space is exhausted, etc.

	     Note that in-place editing with -I still takes place in a single
	     continuous line address space covering all files, although each
	     file preserves its individuality instead of forming one output
	     stream.  The line counter is never reset between files, address
	     ranges can span file boundaries, and the “$” address matches only
	     the last line of the last file.  (See Sed Addresses.)  That can
	     lead to unexpected results in many cases of in-place editing,
	     where using -i is desired.

     -i extension
	     Edit files in-place similarly to -I, but treat each file indepen‐
	     dently from other files.  In particular, line numbers in each
	     file start at 1, the “$” address matches the last line of the
	     current file, and address ranges are limited to the current file.
	     (See Sed Addresses.)  The net result is as though each file were
	     edited by a separate sed instance.

     -l	     Make output line buffered.

     -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.

     -r	     Same as -E for compatibility with GNU sed.

     The form of a sed command is as follows:

	   [address[,address]]function[arguments]

     Whitespace may be inserted before the first address and the function por‐
     tions of the command.

     Normally, sed cyclically copies a line of input, not including its termi‐
     nating newline character, into a pattern space, (unless there is some‐
     thing left after a “D” function), applies all of the commands with
     addresses that select that pattern space, copies the pattern 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 subsequent retrieval.

Sed Addresses
     An address is not required, but if specified must have one of the follow‐
     ing formats:

	   ·   a number that counts input lines cumulatively across input
	       files (or in each file independently if a -i option is in
	       effect);

	   ·   a dollar (“$”) character that addresses the last line of input
	       (or the last line of the current file if a -i option was speci‐
	       fied);

	   ·   a context address that consists of a regular expression pre‐
	       ceded and followed by a delimiter. The closing delimiter can
	       also optionally be followed by the “I” character, to indicate
	       that the regular expression is to be matched in a case-insensi‐
	       tive way.

     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 an inclusive range.  This range
     starts with the first pattern space that matches the first address.  The
     end of the range is the next following pattern space that matches the
     second address.  If the second address is a number less than or equal to
     the line number first selected, only that line is selected.  The number
     in the second address may be prefixed with a (“+”) to specify the number
     of lines to match after the first pattern.	 In the case when the second
     address is a context address, sed does not re-match the second address
     against the pattern space that matched the first address.	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 regular expressions used in sed, by default, are basic regular
     expressions (BREs, see re_format(7) for more information), but extended
     (modern) regular expressions can be used instead if the -E flag is given.
     In addition, sed has the following two additions to regular expressions:

     1.	  In a context address, any character other than a backslash (“\”) or
	  newline character may be used to delimit the regular expression.
	  The opening delimiter needs to be preceded by a backslash unless it
	  is a slash.  For example, the context address \xabcx is equivalent
	  to /abc/.  Also, putting a backslash character before the delimiting
	  character within the regular expression 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 cannot, however, use a literal newline character
	  in an address or in the substitute command.

     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 sub‐
     stitute 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 command 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 func‐
     tions 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 specified, 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 pat‐
	     tern 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
		   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 new‐
	     line.  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 character 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 con‐
	     dition 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 newline 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:

		   N	   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.

		   I	   Match the regular expression in a case-insensitive
			   way.

     [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 corresponding characters from string2.  Any char‐
	     acter 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 character, 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 new‐
	     line 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 charac‐
	     ters in the file are “#n”, the default output is suppressed.
	     This is the same as specifying the -n option on the command line.

ENVIRONMENT
     The COLUMNS, LANG, LC_ALL, LC_CTYPE and LC_COLLATE environment variables
     affect the execution of sed as described in environ(7).

EXIT STATUS
     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 utility is expected to be a superset of the IEEE Std 1003.2
     (“POSIX.2”) specification.

     The -E, -I, -a and -i options, the prefixing “+” in the second member of
     an address range, as well as the “I” flag to the address regular expres‐
     sion and substitution command are non-standard FreeBSD extensions and may
     not be available on other operating systems.

HISTORY
     A sed command, written by L. E. McMahon, appeared in Version 7 AT&T UNIX.

AUTHORS
     Diomidis D. Spinellis ⟨dds@FreeBSD.org⟩

BUGS
     Multibyte characters containing a byte with value 0x5C (ASCII ‘\’) may be
     incorrectly treated as line continuation characters in arguments to the
     “a”, “c” and “i” commands.	 Multibyte characters cannot be used as delim‐
     iters with the “s” and “y” commands.

BSD				 May 24, 2009				   BSD
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