About

Basic grep already supports some patterns, like glob and regex.

To extend the matching to be more powerful, you can use extended grep.

Usage

egrep PATTERN PATH

Or grep -e in place of egrep.

Examples

$ egrep "support|help|windows" myfile.txt

$ egrep '^[a-zA-Z]+$' myfile.txt

$ egrep -c '^begin|end$' myfile.txt

Note that brackets are not needed in the simple case.

$ egrep 'Foo bar|baz: ' myfile.txt
$ egrep '(Foo bar)|(baz: )' myfile.txt

But are meaningful here:

$ egrep -H '[^0] to (add|destroy)' *