SED(1) sed 4.2.2 SED(1)
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December 2012
NAME
sed - stream editor for filtering and transforming text
SYNOPSIS
sed [OPTION]... {script-only-if-no-other-script} [input-file]...
DESCRIPTION
Sed is a stream editor. A stream editor is used to perform basic text
transformations on an input stream (a file or input from a pipeline).
While in some ways similar to an editor which permits scripted edits
(such as ed), sed works by making only one pass over the input(s), and
is consequently more efficient. But it is sed's ability to filter
text in a pipeline which particularly distinguishes it from other
types of editors.
-n, --quiet, --silent
suppress automatic printing of pattern space
-e script, --expression=script
add the script to the commands to be executed
-f script-file, --file=script-file
add the contents of script-file to the commands to be executed
--follow-symlinks
follow symlinks when processing in place
-i[SUFFIX], --in-place[=SUFFIX]
edit files in place (makes backup if SUFFIX supplied)
-l N, --line-length=N
specify the desired line-wrap length for the `l' command
--posix
disable all GNU extensions.
-r, --regexp-extended
use extended regular expressions in the script.
-s, --separate
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consider files as separate rather than as a single continuous
long stream.
-u, --unbuffered
load minimal amounts of data from the input files and flush the
output buffers more often
-z, --null-data
separate lines by NUL characters
--help
display this help and exit
--version
output version information and exit
If no -e, --expression, -f, or --file option is given, then the first
non-option argument is taken as the sed script to interpret. All
remaining arguments are names of input files; if no input files are
specified, then the standard input is read.
GNU sed home page: <http://www.gnu.org/software/sed/>. General help
using GNU software: <http://www.gnu.org/gethelp/>. E-mail bug reports
to: <bug-sed@gnu.org>. Be sure to include the word ``sed'' somewhere
in the ``Subject:'' field.
COMMAND SYNOPSIS
This is just a brief synopsis of sed commands to serve as a reminder
to those who already know sed; other documentation (such as the
texinfo document) must be consulted for fuller descriptions.
Zero-address ``commands''
: label
Label for b and t commands.
#comment
The comment extends until the next newline (or the end of a -e
script fragment).
} The closing bracket of a { } block.
Zero- or One- address commands
= Print the current line number.
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a \
text Append text, which has each embedded newline preceded by a
backslash.
i \
text Insert text, which has each embedded newline preceded by a
backslash.
q [exit-code]
Immediately quit the sed script without processing any more
input, except that if auto-print is not disabled the current
pattern space will be printed. The exit code argument is a GNU
extension.
Q [exit-code]
Immediately quit the sed script without processing any more
input. This is a GNU extension.
r filename
Append text read from filename.
R filename
Append a line read from filename. Each invocation of the command
reads a line from the file. This is a GNU extension.
Commands which accept address ranges
{ Begin a block of commands (end with a }).
b label
Branch to label; if label is omitted, branch to end of script.
c \
text Replace the selected lines with text, which has each embedded
newline preceded by a backslash.
d Delete pattern space. Start next cycle.
D If pattern space contains no newline, start a normal new cycle as
if the d command was issued. Otherwise, delete text in the
pattern space up to the first newline, and restart cycle with the
resultant pattern space, without reading a new line of input.
h H Copy/append pattern space to hold space.
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g G Copy/append hold space to pattern space.
l List out the current line in a ``visually unambiguous'' form.
l width
List out the current line in a ``visually unambiguous'' form,
breaking it at width characters. This is a GNU extension.
n N Read/append the next line of input into the pattern space.
p Print the current pattern space.
P Print up to the first embedded newline of the current pattern
space.
s/regexp/replacement/
Attempt to match regexp against the pattern space. If
successful, replace that portion matched with replacement. The
replacement may contain the special character & to refer to that
portion of the pattern space which matched, and the special
escapes \1 through \9 to refer to the corresponding matching
sub-expressions in the regexp.
t label
If a s/// has done a successful substitution since the last input
line was read and since the last t or T command, then branch to
label; if label is omitted, branch to end of script.
T label
If no s/// has done a successful substitution since the last
input line was read and since the last t or T command, then
branch to label; if label is omitted, branch to end of script.
This is a GNU extension.
w filename
Write the current pattern space to filename.
W filename
Write the first line of the current pattern space to filename.
This is a GNU extension.
x Exchange the contents of the hold and pattern spaces.
y/source/dest/
Transliterate the characters in the pattern space which appear in
source to the corresponding character in dest.
Addresses Sed commands can be given with no addresses, in which case
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the command will be executed for all input lines; with one address, in
which case the command will only be executed for input lines which
match that address; or with two addresses, in which case the command
will be executed for all input lines which match the inclusive range
of lines starting from the first address and continuing to the second
address. Three things to note about address ranges: the syntax is
addr1,addr2 (i.e., the addresses are separated by a comma); the line
which addr1 matched will always be accepted, even if addr2 selects an
earlier line; and if addr2 is a regexp, it will not be tested against
the line that addr1 matched.
After the address (or address-range), and before the command, a ! may
be inserted, which specifies that the command shall only be executed
if the address (or address-range) does not match.
The following address types are supported:
number
Match only the specified line number (which increments
cumulatively across files, unless the -s option is specified on
the command line).
first~step
Match every step'th line starting with line first. For example,
``sed -n 1~2p'' will print all the odd-numbered lines in the
input stream, and the address 2~5 will match every fifth line,
starting with the second. first can be zero; in this case, sed
operates as if it were equal to step. (This is an extension.)
$ Match the last line.
/regexp/
Match lines matching the regular expression regexp.
\cregexpc
Match lines matching the regular expression regexp. The c may be
any character.
GNU sed also supports some special 2-address forms:
0,addr2
Start out in "matched first address" state, until addr2 is found.
This is similar to 1,addr2, except that if addr2 matches the very
first line of input the 0,addr2 form will be at the end of its
range, whereas the 1,addr2 form will still be at the beginning of
its range. This works only when addr2 is a regular expression.
addr1,+N
Will match addr1 and the N lines following addr1.
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addr1,~N
Will match addr1 and the lines following addr1 until the next
line whose input line number is a multiple of N.
REGULAR EXPRESSIONS
POSIX.2 BREs should be supported, but they aren't completely because
of performance problems. The \n sequence in a regular expression
matches the newline character, and similarly for \a, \t, and other
sequences.
BUGS
E-mail bug reports to bug-sed@gnu.org. Also, please include the
output of ``sed --version'' in the body of your report if at all
possible.
AUTHOR
Written by Jay Fenlason, Tom Lord, Ken Pizzini, and Paolo Bonzini.
GNU sed home page: <http://www.gnu.org/software/sed/>. General help
using GNU software: <http://www.gnu.org/gethelp/>. E-mail bug reports
to: <bug-sed@gnu.org>. Be sure to include the word ``sed'' somewhere
in the ``Subject:'' field.
COPYRIGHT
Copyright c 2012 Free Software Foundation, Inc. License GPLv3+: GNU
GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
awk(1), ed(1), grep(1), tr(1), perlre(1), sed.info, any of various
books on sed, the sed FAQ
(http://sed.sf.net/grabbag/tutorials/sedfaq.txt),
http://sed.sf.net/grabbag/.
The full documentation for sed is maintained as a Texinfo manual. If
the info and sed programs are properly installed at your site, the
command
info sed
should give you access to the complete manual.
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