Range Addresses (sed, a stream editor)

4.4 Range Addresses

An address range can be specified by specifying two addresses separated by a comma (,). An address range matches lines starting from where the first address matches, and continues until the second address matches (inclusively):

$ seq 10 | sed -n '4,6p'
4
5
6

If the second address is a regexp, then checking for the ending match will start with the line following the line which matched the first address: a range will always span at least two lines (except of course if the input stream ends).

$ seq 10 | sed -n '4,/[0-9]/p'
4
5

If the second address is a number less than (or equal to) the line matching the first address, then only the one line is matched:

$ seq 10 | sed -n '4,1p'
4

GNU sed also supports some special two-address forms; all these are GNU extensions:

0,/regexp/

A line number of 0 can be used in an address specification like 0,/regexp/ so that sed will try to match regexp in the first input line too. In other words, 0,/regexp/ is similar to 1,/regexp/, except that if addr2 matches the very first line of input the 0,/regexp/ form will consider it to end the range, whereas the 1,/regexp/ form will match the beginning of its range and hence make the range span up to the second occurrence of the regular expression.

Note that this is the only place where the 0 address makes sense; there is no 0-th line and commands which are given the 0 address in any other way will give an error.

The following examples demonstrate the difference between starting with address 1 and 0:

$ seq 10 | sed -n '1,/[0-9]/p'
1
2

$ seq 10 | sed -n '0,/[0-9]/p'
1

addr1,+N

Matches addr1 and the N lines following addr1.

$ seq 10 | sed -n '6,+2p'
6
7
8

addr1 can be a line number or a regular expression.

addr1,~N

Matches addr1 and the lines following addr1 until the next line whose input line number is a multiple of N. The following command prints starting at line 6, until the next line which is a multiple of 4 (i.e. line 8):

$ seq 10 | sed -n '6,~4p'
6
7
8

addr1 can be a line number or a regular expression.