I have this regular express (?<=heads\/)(.*?)(?=\n)
and you can see it working here
http://regexr.com?347dm
I need this regex to work in the grep command but I'm getting this error.
$ grep -Eio '(?<=heads\/)(.*?)(?=\n)' text.txt
grep: repetition-operator operand invalid
It works great in ack but I dont have ack on the machine I need to run this on.
ack text.txt -o --match '(?<=heads\/)(.*?)(?=\n)'
text.txt
74f3649af36984e1b784e46502fe318e91d29570 HEAD
06d4463ab47a6246e6bd94dc3b9267d59fc16c2e refs/heads/ARC
0597e13c22b6397a1b260951f9d064f668b26f08 refs/heads/LocationAge
e7e1ed942d15efb387c878b9d0335b37560c8807 refs/heads/feature/311-312-breaking-banner-updates
d0b2632b465702d840a358d0b192198ae505011c refs/heads/gulf-news
509173eafc6792739787787de0d23b0c804d4593 refs/heads/jbb-new-applicationdidfinishlaunching
1e7b03ce75b1a7ba47ff4fb5128bc0bf43a7393b refs/heads/locationdebug
74f3649af36984e1b784e46502fe318e91d29570 refs/heads/master
5d2ede384325877c24db7ba1ba0338dc7b7f84fb refs/heads/mixed-media
3f3b6a81dd3baea8744aec6b95c2fe4aaeb20ea3 refs/heads/post-onezero
4198a43aab2dfe72d7ae9e9e53fbb401fc9dac1f refs/heads/whitelabel
76741013b3b2200de29f53800d51dfd6dc7bac5e refs/tags/r10
fc53b1a05dad3072614fb397a228819a67615b82 refs/tags/r10^{}
afdcfd970c9387f6fda0390ef781c2776aa666c3 refs/tags/r11
grep does not support the (?<=...)
or *?
or (?=...)
operators. See this table.