Introduction to grep

This article was originally published on bmf-tech.com.

Overview

grep is a command I used casually, so I decided to investigate it more thoroughly.

Basics

grep search-pattern filename

You can use wildcards, so for example, if you want to target all files in the current directory, you can do it like this:

grep "foo" ./*

If you want to include directories under the current directory, use the -r option.

grep -r "foo" ./*

Options

Here are some commonly used options.

-i

• Ignore case distinctions

-v

• Select non-matching lines

-n

• Display line numbers with output lines

-l

• Display file names with matches

-L

• Display file names without matches

-r

• Include directories in the search

-w

• Search for whole words (exact match)

Practical Use

OR Search

grep "foo\|bar" ./*

You need to escape with \.

AND Search

grep "foo" ./* | grep "bar"

Exclude Specific Directories

grep "foo" ./* --exclude-dir=vendor

References

• @IT - 【 grep 】Command: Extract lines containing specific characters