sed - stream editor
sed [-an] command [file ...]
sed [-an] [-e command] [-f command_file] [file ...]
The sed utility reads the specified files, or the standard
input if no
files are specified, modifying the input as specified by a
list of commands.
The input is then written to the standard output.
A single command may be specified as the first argument to
sed. Multiple
commands may be specified by using the -e or -f options.
All commands
are applied to the input in the order they are specified regardless of
their origin.
The options are as follows:
-a The files listed as parameters for the `w' functions
are created
(or truncated) before any processing begins, by default. The -a
option causes sed to delay opening each file until a
command containing
the related `w' function is applied to a
line of input.
-e command
Append the editing commands specified by the command
argument to
the list of commands.
-f command_file
Append the editing commands found in the file
command_file to the
list of commands. The editing commands should each
be listed on
a separate line.
-n By default, each line of input is echoed to the
standard output
after all of the commands have been applied to it.
The -n option
suppresses this behavior.
The form of a sed command is as follows:
[address[,address]]function[arguments]
Whitespace may be inserted before the first address and the
function portions
of the command.
Normally, sed cyclically copies a line of input, not including its terminating
newline character, into a pattern space, (unless
there is something
left after a `D' function), applies all of the commands with addresses
that select that pattern space, copies the pattern
space to the
standard output, appending a newline, and deletes the pattern space.
Some of the functions use a hold space to save all or part
of the pattern
space for subsequent retrieval.
An address is not required, but if specified must be a number (that
counts input lines cumulatively across input files), a dollar character
(`$') that addresses the last line of input, or a context
address (which
consists of a regular expression preceded and followed by a
delimiter).
A command line with no addresses selects every pattern
space.
A command line with one address selects all of the pattern
spaces that
match 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
that line is
selected.) Starting at the first line following the selected range, sed
starts looking again for the first address.
Editing commands can be applied to non-selected pattern
spaces by use of
the exclamation character (`!') function.
SED REGULAR EXPRESSIONS [Toc] [Back] The sed regular expressions are basic regular expressions
(BRE's; see
re_format(7) for more information). In addition, sed has
the following
two additions to BRE's:
1. In a context address, any character other than a backslash (`') or
newline character may be used to delimit the regular
expression.
Also, putting a backslash character before the delimiting character
causes the character to be treated literally. For example, in the
context address cfx, the RE delimiter is an `x' and the
second
`x' stands for itself, so that the regular expression is
``abcxdef''.
2. The escape sequence matches a newline character embedded in the
pattern space. You can't, however, use a literal newline character
in an address or in the substitute command.
One special feature of sed regular expressions is that they
can default
to the last regular expression used. If a regular expression is empty,
i.e., just the delimiter characters are specified, the last
regular expression
encountered is used instead. The last regular expression is defined
as the last regular expression used as part of an address or substitute
command, and at run-time, not compile-time. For example, the
command ``/abc/s//XXX/'' will substitute ``XXX'' for the
pattern ``abc''.
In the following list of commands, the maximum number of
permissible addresses
for each command is indicated by [0addr], [1addr],
or [2addr],
representing zero, one, or two addresses.
The argument text consists of one or more lines. To embed a
newline in
the text, precede it with a backslash. Other backslashes in
text are
deleted and the following character taken literally.
The `r' and `w' functions take an optional file parameter,
which should
be separated from the function letter by whitespace. Each
file given as
an argument to sed is created (or its contents truncated)
before any input
processing begins.
The `b', `r', `s', `t', `w', `y', `!', and `:' functions all
accept additional
arguments. The following synopses indicate which arguments have
to be separated from the function letters by whitespace
characters.
Two of the functions take a function-list. This is a list
of sed functions
separated by newlines, as follows:
{ function
function
...
function
}
The `{' can be preceded or followed by whitespace. The
function can be
preceded by whitespace as well. The terminating `}' must be
preceded by
a newline or optional whitespace.
[2addr] function-list
Execute function-list only when the pattern space
is selected.
[1addr]a text
Write text to standard output immediately before
each attempt
to read a line of input, whether by executing the
`N' function
or by beginning a new cycle.
[2addr]b[label]
Branch to the `:' function with the specified label. If the
label is not specified, branch to the end of the
script.
[2addr]c text
Delete the pattern space. With 0 or 1 address or
at the end of
a 2-address range, text is written to the standard
output.
[2addr]d Delete the pattern space and start the next cycle.
[2addr]D Delete the initial segment of the pattern space
through the
first newline character and start the next cycle.
[2addr]g Replace the contents of the pattern space with the
contents of
the hold space.
[2addr]G Append a newline character followed by the contents of the hold
space to the pattern space.
[2addr]h Replace the contents of the hold space with the
contents of the
pattern space.
[2addr]H Append a newline character followed by the contents of the pattern
space to the hold space.
[1addr]i text
Write text to the standard output.
[2addr]l (The letter ell.) Write the pattern space to the
standard output
in a visually unambiguous form. This form is
as follows:
backslash \
alert
form-feed
newline
carriage-return
tab
vertical tab
Non-printable characters are written as three-digit octal numbers
(with a preceding backslash) for each byte in
the character
(most significant byte first). Long lines are
folded, with
the point of folding indicated by displaying a
backslash followed
by a newline. The end of each line is
marked with a `$'.
[2addr]n Write the pattern space to the standard output if
the default
output has not been suppressed, and replace the
pattern space
with the next line of input.
[2addr]N Append the next line of input to the pattern
space, using an
embedded newline character to separate the appended material
from the original contents. Note that the current
line number
changes.
[2addr]p Write the pattern space to standard output.
[2addr]P Write the pattern space, up to the first newline
character to
the standard output.
[1addr]q Branch to the end of the script and quit without
starting a new
cycle.
[1addr]r file
Copy the contents of file to the standard output
immediately
before the next attempt to read a line of input.
If file cannot
be read for any reason, it is silently ignored
and no error
condition is set.
[2addr]s/re/replacement/flags
Substitute the replacement string for the first
instance of the
regular expression in the pattern space. Any
character other
than backslash or newline can be used instead of a
slash to delimit
the RE and the replacement. Within the RE
and the replacement,
the RE delimiter itself can be used as
a literal
character if it is preceded by a backslash.
An ampersand (`&') appearing in the replacement is
replaced by
the string matching the RE. The special meaning
of `&' in this
context can be suppressed by preceding it by a
backslash. The
string ` matched by the corresponding backreference expression (see
re_format(7)).
A line can be split by substituting a newline
character into
it. To specify a newline character in the replacement string,
precede it with a backslash.
The value of flags in the substitute function is
zero or more
of the following:
0 ... 9
Make the substitution only for the
N'th occurrence
of the regular expression in
the pattern
space.
g Make the substitution for all nonoverlapping
matches of the regular expression,
not just the
first one.
p Write the pattern space to standard
output if a
replacement was made. If the replacement string
is identical to that which it replaces, it is
still considered to have been a replacement.
w file Append the pattern space to file if
a replacement
was made. If the replacement string
is identical
to that which it replaces, it is
still considered
to have been a replacement.
[2addr]t[label]
Branch to the `:' function bearing the label if
any substitutions
have been made since the most recent reading
of an input
line or execution of a `t' function. If no label
is specified,
branch to the end of the script.
[2addr]w file
Append the pattern space to the file.
[2addr]x Swap the contents of the pattern and hold spaces.
[2addr]y/string1/string2/
Replace all occurrences of characters in string1
in the pattern
space with the corresponding characters from
string2. Any
character other than a backslash or newline can be
used instead
of a slash to delimit the strings. Within string1
and string2,
a backslash followed by any character other than a
newline is
that literal character, and a backslash followed
by an `n' is
replaced by a newline character.
[2addr]!function, [2addr]!function-list
Apply the function or function-list only to the
lines that are
not selected by the address(es).
[0addr]:label
This function does nothing; it bears a label to
which the `b'
and `t' commands may branch.
[1addr]= Write the line number to the standard output followed by a newline
character.
[0addr] Empty lines are ignored.
[0addr]# The `#' and the remainder of the line are ignored
(treated as a
comment), with the single exception that if the
first two characters
in the file are `#n', the default output is
suppressed.
This is the same as specifying the -n option on
the command
line.
The sed utility exits 0 on success or >0 if an error occurred.
awk(1), ed(1), grep(1), regex(3), re_format(7)
"SED -- A Non-interactive Text Editor",
/usr/share/doc/usd/15.sed/.
The sed function is expected to be a superset of the IEEE
Std 1003.2
(``POSIX.2'') specification.
A sed command appeared in Version 7 AT&T UNIX.
OpenBSD 3.6 December 30, 1993
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