About

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

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

You won’t get an error using grep here in place of egrep - you’ll probably just get an error.

Usage

$ egrep PATTERN PATH

Or grep -e in place of egrep.

Examples

Find numbers:

$ egrep '[0-9]'

Note that some versions of egrep will allow \d but not on WSL, from my testing.

Find alphabetic characters:

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

Find alphanumeric characters:

$ egrep 'My prefix \w\w\w\w'

Find words:

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

Add -c for count.

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

$ egrep '^[a-z -]+:' Makefile

Find Go version in a Go module file.

$ egrep 'go \d+\.\d+' go.mod
go 1.15

Note that brackets are optional in the simple case.

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

But brackets are meaningful here:

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