sed(1)
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sed Command
stream editor
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SYNTAX
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.
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.
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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.
You can apply editing commands only to non-selected pattern
spaces with the negation function ! (below).
The following list of functions gives the maximum number of
permissible addresses for each function 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 label. If label is
empty, branch to the end of the script.
(2)c\
text Change. Delete the pattern space. With 0 or 1 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.
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(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-printing characters are spelled
in two-digit ASCII 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.
(1)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
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 to 512. Substitute for just the nth
occurrence (on the line) of the regular
expression.
g Global. Substitute for all nonoverlapping
instances of the regular expression, not 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
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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
Takes no action; 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 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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