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sed - a Stream EDitor
sed [-n] [-V] [--quiet] [--silent] [--version] [--help]
[-e script] [--expression=script]
[-f script-file] [--file=script-file]
[script-if-no-other-script]
[file...]
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), works by making only one pass over the input(s), and is consequently
more efficient. But it is 's ability to filter text in a pipeline which particularly
distinguishes it from other types of editors.
may be invoked with
the following command-line options:
- -V
- --version
- Print out the version of sed
that is being run and a copyright notice, then exit.
- -h
- --help
- Print a usage
message briefly summarizing these command-line options and the bug-reporting
address, then exit.
- -n
- --quiet
- --silent
- By default, will print out the pattern
space at the end of each cycle through the script. These options disable
this automatic printing, and will only produce output when explicitly
told to via the p command.
- -e script
- --expression=script
- Add the commands in
script to the set of commands to be run while processing the input.
- -f script-file
- --file=script-file
- Add the commands contained in the file script-file to the
set of commands to be run while processing the input.
If no -e,-f,--expression,
or --file options are given on the command-line, then the first non-option
argument on the command line is taken to be the script to be executed.
If
any command-line parameters remain after processing the above, these parameters
are interpreted as the names of input files to be processed. A file name
of - refers to the standard input stream. The standard input will processed
if no file names are specified.
Command Synopsis This is just a brief synopsis
of 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
preceeded by a backslash.
- i \
- text
- Insert text, which has each embedded newline
preceeded by a backslash.
- q
- Immediately quit the script without processing
any more input, except that if auto-print is not diabled the current pattern
space will be printed.
- r filename
- Append text read from filename. 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.
- t label
- If a s/// has done a successful substitution since the last input line
was read and since the last t command, then 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 preceeded by a backslash.
- d
- Delete
pattern space. Start next cycle.
- D
- Delete up to the first embedded newline
in the pattern space. Start next cycle, but skip reading from the input
if there is still data in the pattern space.
- h H
- Copy/append pattern space
to hold space.
- g G
- Copy/append hold space to pattern space.
- x
- Exchange the
contents of the hold and pattern spaces.
- l
- List out the current line in
a ``visually unambiguous'' form.
- 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.
- w
- filename Write the current pattern space to filename.
- y/source/dest/
- Transliterate the characters in the pattern space which appear in source
to the corresponding character in dest.
Addresses 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.
- 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. (This is a GNU 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.
Regular expressions POSIX.2 BREs should be supported,
but they aren't completely yet. The \n sequence in a regular expression matches
the newline character. There are also some GNU extensions. [XXX FIXME: more
needs to be said. At the very least, a reference to another document which
describes what is supported should be given.] Miscellaneous notes This version
of sed supports a \<newline> sequence in all regular expressions, the replacement
part of a substitute (s) command, and in the source and dest parts of a
transliterate (y) command. The \ is stripped, and the newline is kept. SEE
ALSO awk(1)
, ed(1)
, expr(1)
, emacs(1)
, perl(1)
, tr(1)
, vi(1)
, regex(5)
[well, one ought to be written... XXX], sed.info, any of various books on ,
the FAQ (http://www.wollery.demon.co.uk/sedtut10.txt,
http://www.ptug.org/sed/sedfaq.htm).
BUGS
E-mail bug reports to bug-gnu-utils@gnu.org. Be sure to include the word
``sed'' somewhere in the ``Subject:'' field.
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