NAME
sed – stream editor |
SYNOPSIS
sed [ –n ] [ –g ] [ –e script ] [ –f sfile ] [ file ... ] |
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's, the option –e may be
omitted. The –n option suppresses the default
output; –g causes all substitutions to be global, as if suffixed
g.
A script consists of editing commands, one per line, of the following
form:
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, /regular–expression/, in the style of regexp(6), with the added convention that \n matches a newline embedded in 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 to non–selected pattern spaces by use of the negation function ! (below). An argument denoted text consists of one or more lines, all but the last of which end with \ to hide the newline. 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.
An argument denoted rfile or wfile 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 120 distinct
wfile arguments.
w wfile Write. Append the pattern space to wfile. x Exchange the contents of the pattern and hold spaces. y/string1/string2/
# Comment. Ignore the rest of the line. : label This command does nothing; it bears a label for b and t commands to branch to. = Place the current line number on the standard output as a line. { Execute the following commands through a matching } only when the pattern space is selected.
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EXAMPLES
sed 10q file
/^$/d drop empty lines s/ */\ replace blanks by newlines /g /^$/d' chapter*
${
//N if current line is empty, append next line /^\n$/D' if two lines are empty, delete the first
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SOURCE
/sys/src/cmd/sed.c |
SEE ALSO
ed(1), grep(1), awk(1), lex(1), sam(1), regexp(6) L. E. McMahon, `SED -- A Non–interactive Text Editor', Unix Research System Programmer's Manual, Volume 2. |
BUGS
If input is from a pipe, buffering may consume characters beyond
a line on which a q command is executed. |