Regex match string that starts with but does not include

Question

I'm trying to match file paths that start with any string from a list. This is what I am using for that:

^/(dir1|dir2|dir3|tmp|dir4)/

I'm also trying to match all paths that start with /tmp/ but do not contain special after that.

This should match:

/tmp/subdir/filename.ext

But this should not:

/tmp/special/filename.ext

I can't seem to find a way to get this done. Any suggestions would be greatly appreciated.

A negative lookahead that is if your regex engine supported it `(?!special)`. — HamZa, Nov 05 '13 at 12:49
possible duplicate of [Regex lookahead, lookbehind and atomic groups](http://stackoverflow.com/questions/2973436/regex-lookahead-lookbehind-and-atomic-groups) — HamZa, Nov 05 '13 at 12:52

score 9 · Accepted Answer · answered Nov 05 '13 at 12:56

9

Try ^(?i)/(dir1|dir2|dir3|tmp(?!\/(special))|dir4)/.*

(?i) = Case insesitivity this will match SpEcial, SPECial, SpEcIAL etc.

(?!\/(special)) = Negative lookahead for the '/special'

answered Nov 05 '13 at 12:56

Srb1313711

This answer works just as well in my case, as the one from @grexter89 (since I need the match to be case sensitive), but your's is more comprehensive. Thanks – Bogdan Nov 05 '13 at 13:08

bukart · Answer 2 · 2013-11-05T13:10:49.293

8

try this

^((?:dir1|dir2|dir3|dir4|tmp(?!/special)).*)$

Regular expression visualization

edited Nov 05 '13 at 13:10

answered Nov 05 '13 at 12:49

bukart

Can you explain '?:' I have not seen this used before? – Srb1313711 Nov 05 '13 at 13:00
3

(?:....) builds a group, but it doesn't create a reference, so there's no special result for the expression inside the brackets – bukart Nov 05 '13 at 13:01

score 1 · Answer 3 · edited Nov 05 '13 at 13:02

1

try this ^(dir1|dir2|dir3|tmp(?!\/special)|dir4)

edited Nov 05 '13 at 13:02

HamZa

answered Nov 05 '13 at 12:55

grexter89

3 Answers3