Grep in Shell Script: the Basic you Need to Know

Here you will find out:

• about grep command in Linux shell script

• how to use it

• when DiskInternals can help you

Are you ready? Let's read!

Examples of shell grep commands

All commands are not complex and lend themselves to simple logic. Here are the most important and basic commands for starting a string search.

grep -i 'bar' filename1 - search for the word 'bar' in Linux (case insensitive)

grep 'word' filename2 - search in Linux on any line containing the word “word” in the file name

grep -c 'nixcraft' frontpage.md - search and count the total number of times the line 'nixcraft' appears in a file called frontpage.md

grep -R 'foo' - look for the word “foo” in all files in the directory and in all its subdirectories in Linux

Examples of grep's syntax in Linux

Examples of command syntax are as follows:

These are various commands for finding strings, regular expressions in multiple files, and even in a directory, using recursive mode.

Practical use of grep command

Now, it’s time from theory to approach practice.

1. 1. We start by looking for user boo in the Linux password file. The command looks like this:

The result will look something similar:

You can be case insensitive (whether capital and lowercase letters) for the program will be the same (e.g. ABC, Abc, abc). Then the command will slightly change:

1. 2. If you need to find only a specific word and not words with a common root, you will need this command:

1. 3. You can also search for not one, but two and more words:

These are just a few examples of using grep in the shell script, but in general, it is a very extensive topic with many additional features.