I am on Ubuntu 16.04 and I want to search files for let’s say “if” and I want to the output until “endif”. The file could look like this

if … SOME CODE
endif

I can do this with grep -A9 if my_file | grep -B9 endif. This doesn’t works if the “if” clause is larger than 9 and if several “if” clauses are in the same file and if the first grep command contains several “if” clauses. The option -m1 in the second grep doesn’t help. Nested “if” clauses can be ignored. Has somebody an idea, maybe not with grep?

Difference to How do I grep for multiple patterns on multiple lines?

1. The question asks for a solution with grep which is answered already in the question: grep -A9 if my_file | grep -B9 endif. The solution doesn’t work in my case but would work in the case of the other question.

2. The proposed grep solutions of the other question don’t work (with Ubuntu?): grep: ein nicht geschütztes ^ oder $ wird mit -Pz nicht unterstützt. which is something like grep: a not protected ^ or $ is not supported with -Pz. I use the following:

   root:/tmp# cat file
   Some text
   begin
   Some text goes here.
   end
   Some more text
   root:/tmp# grep -Pzo "^begin\$(.|\n)*^end$" file
   grep: ein nicht geschütztes ^ oder $ wird mit -Pz nicht unterstützt

3. The proposed solutions search only for pattern which start at the beginning of the line if I interpret the proposed solution correctly. Even if I remove ^ the command doesn't work.

4

3 Answers

You can use sed for that:

sed -n '/if/,/endif/p' myfile

• -n don't print anything until we ask for it
• /if/ find the first line with this
• , keep going until...
• /endif/ this is the last line we want
• p print the matched lines

4

Traditional grep is line-oriented. To do multiline matches, you either need to fool it into slurping the whole file by telling it that your input is null terminated e.g.

grep -zPo '(?s)\nif.*\nendif' file

or use a more flexible tool such as pcregrep

pcregrep -M '(?s)\nif.*?\nendif' file

or perl itself

perl -00 -ne 'print if m/^if.*?endif/s' file

Alternatively, for matching structured input in a grep-like way, there's sgrep

sgrep '"if" .. ("endif") containing "SOME CODE"' file

3

A solution awk could look like: awk '/if/,/endif/' file

Of course, it is similar to the solution with sed.

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