nevan king nevan king - 4 months ago 13
Perl Question

What flavour of regular expression is grep?

I'm guessing it's not a Perl Compatible Regular Expression, since there's a special kind of

grep
which is specifically PCRE. What's
grep
most similar to?

Are there any special quirks of
grep
that I need to know about? (I'm used to Perl and the
preg
functions in PHP)

Answer

Default GNU grep behavior is to use a slightly flavorful variant on POSIX basic regular expressions, with a similarly tweaked species of POSIX extended regular expressions for egrep (usually aka grep -E). POSIX ERE is what PHP ereg() uses.

GNU grep also claims to support grep -P for PCRE, by the way. So no terribly special kind of grep required.

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