regexps vs regexps [LWN.net]

regexps vs regexps

Posted Aug 5, 2004 8:22 UTC (Thu) by pkolloch (subscriber, #21709)
In reply to: globs vs regexps by rfunk
Parent article: Bash 3.0 released

Regular expressions are first of all a theoretical concept. In that sense, regular expressions specify a (often infinite) language of accepted words. Fileglobs are usually not quite as powerful, but have a simplified syntax. There are some very frequently used regular expressions syntaxes as nicely described in the referenced WikiPedia page.

If we start nit picking, we should not mistake one of those syntaxes as the one and only real regular expression syntax.

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regexps vs regexps

Posted Aug 5, 2004 14:26 UTC (Thu) by rfunk (subscriber, #4054) [Link]

Regular expressions are first of all a theoretical concept

Yes, I tried to account for that without getting into the theoretical details that I don't remember.

If we start nit picking, we should not mistake one of those syntaxes as the one and only real regular expression syntax.

Except that globs do not have the power required by a true (theoretical) regular expression. They can't express everything that a regular expression can.