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HP-UX 11i Version 3: February 2007

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sed — stream text editor


sed [-n] script [file]...

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


sed copies the named text files (standard input default) to the standard output, edited according to a script containing up to 100 commands. Only complete input lines are processed. Any input text at the end of a file that is not terminated by a new-line character is ignored.


sed recognizes the following options:

-f script_file

Take script from file script_file.

-e script

Edit according to script. If there is just one -e option and no -f options, the flag -e can be omitted.


Suppress the default output.

sed interprets all -e script and -f script_file arguments in the order given. Use caution, if mixing -e and -f options, to avoid unpredictable or incorrect results.

Command Scripts

A script consists of editor 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.

Command Addresses

An address is either a decimal number that counts input lines cumulatively across files, a $ which addresses the last line of input, or a context address; that is, 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 character 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 (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.

sed supports Basic Regular Expression syntax (see regexp(5)).

Editing commands can also be applied to only non-selected pattern spaces by use of the negation function ! (described below).

Command Functions

In the following list of functions, the maximum number of permissible addresses for each function is indicated in parentheses. Other function elements are interpreted as follows:


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 can be used to protect initial blanks and tabs against the stripping that is done on every script line.


Must terminate the command line, and must be preceded by exactly one blank.


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.

sed recognizes the following functions:



Append. Place text on the output before reading next input line.

(2)b label

Branch to the : command bearing label. If no label is specified, branch to the end of the script.



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.


Delete pattern space and start the next cycle.


Delete initial segment of pattern space through first new-line and start the next cycle.


Replace contents of the pattern space with contents of the hold space.


Append contents of hold space to the pattern space.


Replace contents of the hold space with contents of the pattern space.


Append the contents of the pattern space to the hold space.



Insert. Place text on the standard output.


List the pattern space on the standard output in an unambiguous form. Non-printing characters are spelled in three-digit octal number format (with a preceding backslash), and long lines are folded.


Copy the pattern space to the standard output if the default output has not been suppressed (by the -n option on the command line or the #n command in the script file). Replace the pattern space with the next line of input.


Append the next line of input to the pattern space with an embedded new-line. (The current line number changes.)


Print. Copy the pattern space to the standard output.


Copy the initial segment of the pattern space through the first new-line to the standard output.


Quit. Branch to the end of the script. Do not start a new cycle.

(1)r rfile

Read contents of rfile and place on output before reading the next input line.

(2)s/regular expression/replacement/flags

Substitute replacement string for instances of regular expression in the pattern space. Any character can be used instead of /. For a fuller description see ed(1). flags is zero or more of:


n=1-2048 (LINE_MAX). Substitute for just the nth occurrence of regular expression in the pattern space.


Global. Substitute for all non-overlapping instances of regular expression rather than just the first one.


Print the pattern space if a replacement was made and the default output has been suppressed (by the -n option on the command line or the #n command in the script file).

Under the UNIX Standard environment (see standards(5)), the pattern space is printed twice, if the -n option is not specified on the command line.

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.


Exchange the contents of the pattern and hold spaces.


Transform. Replace all occurrences of characters in string1 with the corresponding character in string2. The lengths of string1 and string2 must be equal.

Any character other than backslash or newline can be used instead of slash to delimit the two strings.

If a backslash character is immediately followed by another backslash character in string1 or string2, the two backslash characters will be handled as a single literal backslash character.

The delimiter itself can be used as a literal character in string1 and string2 if it is preceded by a backslash. The only exception is character "n" as the delimiter, because backslash-n, "\n", will be interpreted as a newline.

The meaning of a backslash is undefined if it is followed by any character that is not "n", a backslash, or the delimiter character.

(2)! function

Don't. Apply the function (or group, if function is {) only to lines not selected by the address or addresses.

(0): 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. The syntax is:

{ cmd1 cmd2 cmd3 . . . }


An empty command is ignored.


If a # appears as the first character on the first line of a script file, that entire line is treated as a comment with one exception: If the character after the # is an n, the default output is suppressed. The rest of the line after #n is also ignored. A script file must contain at least one non-comment line.


For information about the UNIX Standard environment, see standards(5).

Environment Variables

LANG provides a default value for the internationalization variables that are unset or null. If LANG is unset or null, the default value of "C" (see lang(5)) is used. If any of the internationalization variables contains an invalid setting, sed will behave as if all internationalization variables are set to "C". See environ(5).

LC_ALL If set to a non-empty string value, overrides the values of all the other internationalization variables.

LC_CTYPE determines the interpretation of text as single and/or multi-byte characters, the classification of characters as printable, and the characters matched by character class expressions in regular expressions.

LC_MESSAGES determines the locale that should be used to affect the format and contents of diagnostic messages written to standard error and informative messages written to standard output.

NLSPATH determines the location of message catalogues for the processing of LC_MESSAGES.

International Code Set Support

Single- and multi-byte character code sets are supported.


Make a simple substitution in a file from the command line or from a shell script, changing abc to xyz:

sed 's/abc/xyz/' file1 >file1.out

Same as above but use shell or environment variables var1 and var2 in search and replacement strings:

sed "s/$var1/$var2/" file1 >file1.out


sed 's/'$var1'/'$var2'/' file1 >file1.out

Multiple substitutions in a single command:

sed -e 's/abc/xyz/' -e 's/lmn/rst/' file1 >file1.out


sed -e 's/abc/xyz/' \ -e 's/lmn/rst/' \ file1 >file1.out


sed limits command scripts to a total of not more than 100 commands.

The hold space is limited to 8192 characters.

sed processes only text files. See the glossary for a definition of text files and their limitations.


sed was developed by OSF and HP.


awk(1), ed(1), grep(1), environ(5), lang(5), regexp(5), standards(5).

sed: A Non-Interactive Streaming Editor tutorial in the Text Processing Users Guide.


sed: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2

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