There are three files in a directory:
ab2 ab23 ab3
When I execute:
ls ab+(2|3)
It displays:
ab2 ab23 ab3
instead of ab2 and ab3 only.
Any ideas why it is like that? Is it a bug?
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John Kugelman
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szawel
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1 Answers
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It's not a bug. +(pattern) matches one or more occurrences of the pattern. +(2|3) will match any combination and any number of 2's and 3's: 2, 3, 23, 32, 222, 333, 3223232323—any of those.
If you want strict alternation without repeats, change + to @:
ab@(2|3)
(Or just use ab[23]. That doesn't even require extglob.)
John Kugelman
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So which pattern catch ab23 ?? try ls ab+(2). It will catch just ab2 – szawel Mar 01 '19 at 21:13
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`ab+(2)` will match `ab2`, `ab22`, `ab222`, etc. – John Kugelman Mar 01 '19 at 21:15
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"or more occurrences" that you are reffering to means that ab2222 also match the pattern. – szawel Mar 01 '19 at 21:16
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@melpomene I know that ab[23] will do the trick but It's not the case. I wonder whether it is a bug. – szawel Mar 01 '19 at 21:18
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@szawel What exactly do you think is a bug? – melpomene Mar 01 '19 at 21:18
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@John Kugelman It looks like it works like you described however it's quite strange for me. Thanks – szawel Mar 01 '19 at 21:22