What flavour of regular expression is grep?

Question

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 simil

Answer 1

Grep is an implementation of POSIX regular expressions. There are two types of posix regular expressions -- basic regular expressions and extended regular expressions. In grep, generally you use the -E option to allow extended regular expressions.