[Chapter 10] 10.3 Syntax of Sed Commands

10.3 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 below.

10.3.1 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 Section 6. 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 accept only one address: a , i , r , q , and = .
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.

10.3.2 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.

[
/


pattern


/
][
,/


pattern


/
]
{



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.