SED
Section: User Commands (1)
Updated: February 2017
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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.
-
-E, -r, --regexp-extended
-
- use extended regular expressions in the script
(for portability use POSIX -E).
-
-s, --separate
-
- consider files as separate rather than as a single,
continuous long stream.
-
--sandbox
-
- operate in sandbox mode.
-
-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>.
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.
- 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.
- 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 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.
- 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: <
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>.
COPYRIGHT
Copyright © 2017 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.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- COMMAND SYNOPSIS
-
- Zero-address ``commands''
-
- Zero- or One- address commands
-
- Commands which accept address ranges
-
- Addresses
-
- REGULAR EXPRESSIONS
-
- BUGS
-
- AUTHOR
-
- COPYRIGHT
-
- SEE ALSO
-
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