Back to Contents
SED(1) User Commands SED(1)
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 dis‐
tinguishes 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 exe‐
cuted
--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.
-E, -r, --regexp-extended
use extended regular expressions in the script (for porta‐
bility use POSIX -E).
-s, --separate
consider files as separate rather than as a single, contin‐
uous long stream.
--sandbox
operate in sandbox mode (disable e/r/w commands).
-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: <https://www.gnu.org/software/sed/>. General
help using GNU software: <https://www.gnu.org/gethelp/>. E-mail
bug reports to: <bug-sed@gnu.org>.
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 descrip‐
tions.
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.
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 cur‐
rent 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 exten‐
sion.
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 embed‐
ded 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.
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 pat‐
tern space.
s/regexp/replacement/
Attempt to match regexp against the pattern space. If suc‐
cessful, 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 cor‐
responding 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 file‐
name. 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 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 com‐
mand will be executed for all input lines which match the inclu‐
sive 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 speci‐
fied 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. Match‐
ing is performed on the current pattern space, which can be
modified with commands such as ``s///''.
\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.
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. The -E option switches to using extended
regular expressions instead; the -E option has been supported for
years by GNU sed, and is now included in POSIX.
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: <https://www.gnu.org/software/sed/>. General
help using GNU software: <https://www.gnu.org/gethelp/>. E-mail
bug reports to: <bug-sed@gnu.org>.
COPYRIGHT
Copyright © 2018 Free Software Foundation, Inc. License GPLv3+:
GNU GPL version 3 or later <https://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/tutori‐
als/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.
sed 4.5 March 2018 SED(1)