How to print lines between two patterns, inclusive or exclusive (in sed, AWK or Perl)?

Question

I have a file like the following and I would like to print the lines between two given patterns PAT1 and PAT2.

Answer 1

What about the classic sed solution?

Print lines between PAT1 and PAT2 - include PAT1 and PAT2

sed -n '/PAT1/,/PAT2/p' FILE

Print lines between PAT1 and PAT2 - exclude PAT1 and PAT2

GNU sed

sed -n '/PAT1/,/PAT2/{/PAT1/!{/PAT2/!p}}' FILE

Any sed¹

sed -n '/PAT1/,/PAT2/{/PAT1/!{/PAT2/!p;};}' FILE

or even (Thanks Sundeep):

GNU sed

sed -n '/PAT1/,/PAT2/{//!p}' FILE

Any sed

sed -n '/PAT1/,/PAT2/{//!p;}' FILE

Print lines between PAT1 and PAT2 - include PAT1 but not PAT2

The following includes just the range start:

GNU sed

sed -n '/PAT1/,/PAT2/{/PAT2/!p}' FILE

Any sed

sed -n '/PAT1/,/PAT2/{/PAT2/!p;}' FILE

Print lines between PAT1 and PAT2 - include PAT2 but not PAT1

The following includes just the range end:

GNU sed

sed -n '/PAT1/,/PAT2/{/PAT1/!p}' FILE

Any sed

sed -n '/PAT1/,/PAT2/{/PAT1/!p;}' FILE

---

¹ Note about BSD/Mac OS X sed

A command like this here:

sed -n '/PAT1/,/PAT2/{/PAT1/!{/PAT2/!p}}' FILE

Would emit an error:

▶ sed -n '/PAT1/,/PAT2/{/PAT1/!{/PAT2/!p}}' FILE
sed: 1: "/PAT1/,/PAT2/{/PAT1/!{/ ...": extra characters at the end of p command

For this reason this answer has been edited to include BSD and GNU versions of the one-liners.

Answer 2

You can do what you want with sed by suppressing the normal printing of pattern space with -n. For instance to include the patterns in the result you can do:

$ sed -n '/PAT1/,/PAT2/p' filename
PAT1
3    - first block
4
PAT2
PAT1
7    - second block
PAT2
PAT1
10    - third block

To exclude the patterns and just print what is between them:

$ sed -n '/PAT1/,/PAT2/{/PAT1/{n};/PAT2/{d};p}' filename
3    - first block
4
7    - second block
10    - third block

Which breaks down as

• sed -n '/PAT1/,/PAT2/ - locate the range between PAT1 and PAT2 and suppress printing;

• /PAT1/{n}; - if it matches PAT1 move to n (next) line;

• /PAT2/{d}; - if it matches PAT2 delete line;

• p - print all lines that fell within /PAT1/,/PAT2/ and were not skipped or deleted.

Answer 3

Alternatively:

sed '/START/,/END/!d;//d'

This deletes all lines except for those between and including START and END, then the //d deletes the START and END lines since // causes sed to use the previous patterns.

Answer 4

This is like a foot-note to the 2 top answers above (awk & sed). I needed to run it on a large number of files, and hence performance was important. I put the 2 answers to a load-test of 10000 times:

sedTester.sh

for i in `seq 10000`;do sed -n '/PAT1/,/PAT2/{/PAT1/!{/PAT2/!p;};}' patternTester >> sedTesterOutput; done

awkTester.sh

 for i in `seq 10000`;do awk '/PAT1/{flag=1; next} /PAT2/{flag=0} flag' patternTester >> awkTesterOutput; done

Here are the results:

zsh sedTester.sh  11.89s user 39.63s system 81% cpu 1:02.96 total
zsh awkTester.sh  38.73s user 60.64s system 79% cpu 2:04.83 total

sed solutions seems to be twice as fast as the awk solution (Mac OS).

Answer 5

Here is another approach

Include both patterns (default)

$ awk '/PAT1/,/PAT2/' file
PAT1
3    - first block
4
PAT2
PAT1
7    - second block
PAT2
PAT1
10    - third block

Mask both patterns

$ awk '/PAT1/,/PAT2/{if(/PAT2|PAT1/) next; print}' file
3    - first block
4
7    - second block
10    - third block

Mask start pattern

$ awk '/PAT1/,/PAT2/{if(/PAT1/) next; print}' file
3    - first block
4
PAT2
7    - second block
PAT2
10    - third block

Mask end pattern

$ awk '/PAT1/,/PAT2/{if(/PAT2/) next; print}' file
PAT1
3    - first block
4
PAT1
7    - second block
PAT1
10    - third block

Answer 6

For completeness, here is a Perl solution:

Print lines between PAT1 and PAT2 - include PAT1 and PAT2

perl -ne '/PAT1/../PAT2/ and print' FILE

or:

perl -ne 'print if /PAT1/../PAT2/' FILE

Print lines between PAT1 and PAT2 - exclude PAT1 and PAT2

perl -ne '/PAT1/../PAT2/ and !/PAT1/ and !/PAT2/ and print' FILE

or:

perl -ne 'if (/PAT1/../PAT2/) {print unless /PAT1/ or /PAT2/}' FILE 

Print lines between PAT1 and PAT2 - exclude PAT1 only

perl -ne '/PAT1/../PAT2/ and !/PAT1/ and print' FILE

Print lines between PAT1 and PAT2 - exclude PAT2 only

perl -ne '/PAT1/../PAT2/ and !/PAT2/ and print' FILE

See also:

• Range operator section in perldoc perlop for more on the /PAT1/../PAT2/ grammar:

Range operator

...In scalar context, ".." returns a boolean value. The operator is bistable, like a flip-flop, and emulates the line-range (comma) operator of sed, awk, and various editors.

• For the -n option, see perldoc perlrun, which makes Perl behave like sed -n.

• Perl Cookbook, 6.8 for a detailed discussion of extracting a range of lines.