Book HomeLinux in a NutshellSearch this book

12.3. Syntax of sed Commands

sed commands have the general form:

[address[,address]][!]command [arguments]

sed commands consist of addresses and editing commands. commands consist of a single letter or symbol; they are described later, alphabetically and by group. arguments include the label supplied to b or t, the filename supplied to r or w, and the substitution flags for s. addresses are described in the next section.

12.3.1. Pattern Addressing

A sed command can specify zero, one, or two addresses. An address can be a line number, the symbol $ (for last line), or a regular expression enclosed in slashes (/pattern/). Regular expressions are described in Chapter 9, "Pattern Matching". Additionally, \n can be used to match any newline in the pattern space (resulting from the N command) but not the newline at the end of the pattern space.

If the Command Specifies Then the Command Is Applied To
No address Each input line.
One address

Any line matching the address. Some commands (a, i, r, q, and =) accept only one address.

Two comma-separated addresses

First matching line and all succeeding lines up to and including a line matching the second address.

An address followed by !

All lines that do not match the address.

12.3.1.1. Examples

s/xx/yy/g                Substitute on all lines (all occurrences)
/BSD/d                   Delete lines containing BSD
/^BEGIN/,/^END/p         Print between BEGIN and END, inclusive
/SAVE/!d                 Delete any line that doesn't contain SAVE
/BEGIN/,/END/!s/xx/yy/g  Substitute on all lines, except between BEGIN and END

Braces ({}) are used in sed to nest one address inside another or to apply multiple commands at the same address:

[/address/[,/address/]]{
command1
command2
}

The opening curly brace must end a line, and the closing curly brace must be on a line by itself. Be sure there are no blank spaces after the braces.



Library Navigation Links

Copyright © 2001 O'Reilly & Associates. All rights reserved.

This HTML Help has been published using the chm2web software.