NAME

sed - stream editor

SYNOPSIS

sed [-n] [-e script] [-f sfile] [file ...]

DESCRIPTION

sed copies the named file (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 identi-
     cal 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.
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 address.  (If the second
     address is a number less than or equal to the line
     number  selected  by  the  first address, only the
     line  corresponding  to  the  first   address   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.  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  nth
                  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. The first occurrence of w will cause wfile to be cleared. Subsequent invocations of w will append. Each time the sed command is used, wfile is overwritten.

(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 characters in string2. string1 and string2 must have the same number of characters.

(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 a line of a script file, then that entire line is treated as a comment, with one exception: if a # appears on the first line and 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).