| SED(1) | General Commands Manual | SED(1) |
sed — stream
editor
sed |
[-aEnru] command
[file ...] |
sed |
[-aEnru] [-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 separated by
newlines or semicolons, or 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:
-aw’ 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-e
command-f
command_file-r-E, for compatibility with GNU
sed.-n-n
option suppresses this behavior.-uThe 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.
By default, sed regular expressions are
basic regular expressions (BREs). Extended regular expressions are supported
using the -E and -r options.
See re_format(7) for more
information on regular expressions. In addition, sed
has the following two additions to BREs:
\’) or newline character may be
used to delimit the regular expression. The opening delimiter should be
preceded by a backslash unless it is a slash. Putting a backslash
character before the delimiting character causes the character to be
treated literally. For example, in the context address \xabc\xdefx, the RE
delimiter is an ‘x’ and the second ‘x’ stands
for itself, so that the regular expression is “abcxdef”.
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.
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.
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.
Write text to the standard output.
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
‘$’.
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 ‘\#’, where
‘#’ is a digit, is replaced by the
text 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:
:’ 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.
#’ 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,
and >0 if an error occurs.
The sed utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
specification.
The flags [-aEru] are extensions to that
specification.
The use of newlines to separate multiple commands on the command
line is non-portable; the use of newlines to separate multiple commands
within a command file (-f
command_file) is portable.
A sed command appeared in
Version 7 AT&T UNIX.
The use of semicolons to separate multiple commands is not
permitted for the following commands: a,
b, c,
i, r,
t, w,
:, and #.
| September 3, 2010 | OpenBSD-5.5 |