how to stop shell script from getting confused by ack PATTERN escapes

Question

I am trying to use ack to search (in Haskell files) for +|+

I looked at ack-grep: chars escaping but this doesn't help

On Mac OS X 10.6 I get the following responses:

$ ack -Q +|+
-bash: +: command not found
Missing option after +
ack: See ack --help, ack --help-types or ack --man for options

$ ack \+\|\+
Unknown option: |
ack: See ack --help, ack --help-types or ack --man for options

$ ack [+][|][+]
-bash: ][+]: command not found
ack: Invalid regex '[+][':
  Unmatched [ in regex; marked by <-- HERE in m/[+][ <-- HERE /

$ ack \Q+|+\E
-bash: +E: command not found

That's basically all the suggestions in the Q&A listed above

The problem here is that you're dealing with two levels of escaping, first `bash` and then `ack` itself. Try putting quotes around the arguments to get them past `bash` then apply the tips in your linked question for `ack`. — hammar, Apr 25 '13 at 09:44

svk · Accepted Answer · 2013-04-25T10:42:16.660

3

This should work as intended:

$ ack "\+\|\+"

(Edited to be correct per your comments. Unquoted pipe is 'or'.)

edited Apr 25 '13 at 10:42

answered Apr 25 '13 at 09:35

svk

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It runs for me, but it matches + ++ whereas I want to match +|+ precisely. – Andrew Butterfield Apr 25 '13 at 09:44
I tried escaping the | using "\+\|\+" - that worked - thanks – Andrew Butterfield Apr 25 '13 at 09:45
I've just realised that quotes appeared in the other question I cited above - but not the answers - hence my missing the answer staring me in the face.... – Andrew Butterfield Apr 25 '13 at 09:56
Thanks for the correction, I edited the answer to be correct so it's not confusing for anyone else later. – svk Apr 25 '13 at 10:43

score 0 · Answer 2 · answered May 16 '13 at 17:20

0

The -Q will quote everything in your search string.

ack --haskell -Q '+|+'

which is easier than

ack --haskell "\+\|\+"

answered May 16 '13 at 17:20

Andy Lester

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how to stop shell script from getting confused by ack PATTERN escapes

2 Answers2