SED(1) (Essential Utilities) SED(1)
NAME
sed - stream editor
SYNOPSIS
sed [-n] [-e script] [-f sfile] [files]
DESCRIPTION
sed copies the named files (standard input default) to the
standard output, edited according to a script of commands.
The -f option causes the script to be taken from file sfile;
these options accumulate. If there is just one -e option
and no -f options, the flag -e may be omitted. The -n
option suppresses the default output. A script consists of
editing commands, one per line, of the following form:
[ address [ , address ] ] function [ arguments ]
In normal operation, sed cyclically copies a line of input
into a pattern space (unless there is something left after a
D command), applies in sequence all commands whose addresses
select that pattern space, and at the end of the script
copies the pattern space to the standard output (except
under -n) and deletes the pattern space.
Some of the commands use a hold space to save all or part of
the pattern space for subsequent retrieval.
An address is either a decimal number that counts input
lines cumulatively across files, a $ that addresses the last
line of input, or a context address, i.e., a /regular
expression/ in the style of ed(1) modified thus:
In a context address, the construction \?regular
expression?, where ? is any character, is
identical to /regular expression/. Note that in
the context address \xabc\xdefx, the second x
stands for itself, so that the regular expression
is abcxdef.
The escape sequence \n matches a new-line embedded in
the pattern space.
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A period . matches any character except the terminal
new-line of the pattern space.
A command line with no addresses selects every pattern
space.
A command line with one address selects each pattern
space that matches the address.
A command line with two addresses selects the inclusive
range from the first pattern space that matches
the first address through the next pattern space
that matches the second. (If the second address
is a number less than or equal to the line number
first selected, only one line is selected.)
Thereafter the process is repeated, looking again
for the first address.
Editing commands can be applied only to non-selected pattern
spaces by use of the negation function ! (below).
In the following list of functions the maximum number of
permissible addresses for each function is indicated in
parentheses.
The text argument consists of one or more lines, all but the
last of which end with \ to hide the new-line. Backslashes
in text are treated like backslashes in the replacement
string of an s command, and may be used to protect initial
blanks and tabs against the stripping that is done on every
script line. The rfile or wfile argument must terminate the
command line and must be preceded by exactly one blank.
Each wfile is created before processing begins. There can
be at most 10 distinct wfile arguments.
(1)a\
text Append. Place text on the output before reading
the next input line.
(2)b label
Branch to the : command bearing the label. If
label is empty, branch to the end of the script.
(2)c\
text Change. Delete the pattern space. With 0 or 1
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address or at the end of a 2-address range, place
text on the output. Start the next cycle.
(2)d Delete the pattern space. Start the next cycle.
(2)D Delete the initial segment of the pattern space
through the first new-line. Start the next cycle.
(2)g Replace the contents of the pattern space by the
contents of the hold space.
(2)G Append the contents of the hold space to the
pattern space.
(2)h Replace the contents of the hold space by the
contents of the pattern space.
(2)H Append the contents of the pattern space to the
hold space.
(1)i\
text Insert. Place text on the standard output.
(2)l List the pattern space on the standard output in
an unambiguous form. Non-printable characters are
displayed in octal notation and long lines are
folded.
(2)n Copy the pattern space to the standard output.
Replace the pattern space with the next line of
input.
(2)N Append the next line of input to the pattern space
with an embedded new-line. (The current line
number changes.)
(2)p Print. Copy the pattern space to the standard
output.
(2)P Copy the initial segment of the pattern space
through the first new-line to the standard output.
(1)q Quit. Branch to the end of the script. Do not
start a new cycle.
(2)r rfile
Read the contents of rfile. Place them on the
output before reading the next input line.
(2)s/regular expression/replacement/flags
Substitute the replacement string for instances of
the regular expression in the pattern space. Any
character may be used instead of /. For a fuller
description see ed(1). Flags is zero or more of:
n n= 1 - 512. Substitute for just the n
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th occurrence of the regular expression.
g Global. Substitute for all
nonoverlapping instances of the regular
expression rather than just the first
one.
p Print the pattern space if a replacement
was made.
w wfile Write. Append the pattern space to
wfile if a replacement was made.
(2)t label
Test. Branch to the : command bearing the label
if any substitutions have been made since the most
recent reading of an input line or execution of a
t. If label is empty, branch to the end of the
script.
(2)w wfile
Write. Append the pattern space to wfile.
(2)x Exchange the contents of the pattern and hold
spaces.
(2)y/string1/string2/
Transform. Replace all occurrences of characters
in string1 with the corresponding character in
string2. The lengths of string1 and string2 must
be equal.
(2)! function
Don't. Apply the function (or group, if function
is {) only to lines not selected by the
address(es).
(0): label
This command does nothing; it bears a label for b
and t commands to branch to.
(1)= Place the current line number on the standard
output as a line.
(2){ Execute the following commands through a matching
} only when the pattern space is selected.
(0) An empty command is ignored.
(0)# If a # appears as the first character on the first
line of a script file, then that entire line is
treated as a comment, with one exception. If the
character after the # is an 'n', then the default
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output will be suppressed. The rest of the line
after #n is also ignored. A script file must
contain at least one non-comment line.
SEE ALSO
awk(1), ed(1), grep(1).
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