For most of the developers and admin , manipulating something after reading a particular file is a common task that most of us hate to do . Grep Command is mostly used in these cases to work with while searching in any kind of text. Grep is Powerful text bases regular expression search utility present in most of linux falvours. In this article we will understand and learn few examples which we use in our shell scripts.
A CentOS/RHEL 7 production server or a Linux VPS .
Installing Grep in Linux/Unix
In most of the cases grep is pre installed in most of the linux distros. But it is possible in some of the linux distros grep might not be present . Have a look how we can install grep .
Installing grep in Ubuntu Distros
sudo apt-get install grep
In RedHat linux Distros yu can install by simply
yum install grep
You can now verify the grep installation by simply typing
Common Grep Command Examples in Linux
The grep command is the one of the most commonly used Unix utility for text based searching in files or any other types . It accepts regular expressions, and can produce output in various formats.
Lets have a look athe various options available in grep command using examples.
How to Search for Lines with a specific pattern
$ grep pattern filename
Lets say i want to find a text name as
John in my text file
grep "John" terminal.txt
This would list down all the lines with the word "John" in my text fle.You can also search in multiple files using the same patttern above
grep "John" file1.txt file2.xt file3.txt