Regular Expression conditionals, e.g. "and" / "or" [closed]

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开发者_Python百科

Closed 9 years ago.

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Is there a way using regular expressions to find

grep 'a &| b &| c' #pseudo code

If 'a' is found also check for 'b' and if 'a' is not found also check for 'b'? etc...

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You can just nest the needed values in parenthesis for and support. Yes there is or | support.

(ab)|(a(c|b))

I would have left it in a comment but don't have enough rep.

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Is this what you mean?

(a)?(b)?(c)?