Any idea what regex engine mod_substitute uses? I'd like to do a little search and replace with it, and I need to escape some characters, so I wanted to see how that particular engine handles that. (I'm guessing it's just \ to escape, but I wanted to know for sure.


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As far as I know, Apache universally uses Perl Compatible Regular Expressions (PCRE). This is stated in the Apache glossary under Regular Expressions. mod_rewrite certainly uses PCRE (as stated in the mod_rewrite docs) and I would assume that mod_substitute does the same.

The backslash (\) escape is used in every regex version I've encountered.

Note that the Substitute directive uses delimiters to separate the different arguments (whereas mod_rewrite uses spaces). The default delimiter is the slash (/), but this can be changed to any other character if your string/regex contains the delimiter. Changing the delimiter is often preferable to escaping these characters in the string/regex.

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