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I am trying to use regex to match strings that not end with 's, I wrote a regex like this: .*[^('s)$]$, but it seems that this regex also cannot match a string that ends with a single s, like cats or dogs, can somebody help? thx

I am using egrep, I have tried like 

^(?!.*'s$).*

or

.*(?<!ab)$

but it seems these not working well

anubhava
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Jasper Zhou
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1 Answers1

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Look-around assertions are traditionally not supported in grep. You may be able to usegrep -v` here:

grep -v "'s$" file

-v option is used for inver-match which is used to return lines are those not matching any of the specified patterns.

However do note in in gnu-grep you can use experimental -P option to use advanced PCRE features such as lookahead and lookbehind assertions.

anubhava
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  • thx in advance, and now I have another question: what if I want to match a string contains a specific string like 'aa' but not end with 's ? It seems I cannot solve this problem with -v :( – Jasper Zhou Jun 04 '19 at 14:34
  • You can use pipeline so `grep 'aa' file | grep -v "'s$"` – anubhava Jun 04 '19 at 14:40