Insight: Grep Command Tutorial In Linux | Beginner’s Guide
Linux is fun to use if you are in love with command. In this post, we are going to talk about one of the Linux command. This post is intended for beginner users. We are going show you the basic example of Grep command. Grep is short form of “global regular expression print” and is considered as one of the most powerful commands in Linux. It is used to search the files. Grep can be used to search the lines in a file which matches a given pattern.
Grep Command Tutorial In Linux
Grep Command Syntax
grep [OPTIONS] PATTERN [FILE...]
Here, OPTIONS can be the zero or the various options which you can find in this link. PATTERN refers to the search pattern and the FILE can be the zero or file names.
How to use Grep to Search for a String in Files
Below is the example to display the lines from the
/opt/filename file containing the string omgfoss . You can use the following command to search the line:
grep omgfoss /etc/filename
Meanwhile, if the string includes spaces, see the example like below:
grep "omg foss " /etc/filename
Meanwhile, To display the lines which doesn’t not match a pattern:
Suppose, you want to display the lines from the
/etc/filename file that do not contain the string
nomatch, then you can use the following command:
grep -v nomatch /etc/filename
Meanwhile, If you want to recursively search for a pattern , use the -r option . In the following example we are searching for the string helloworld in all files inside the /opt directory:
grep -r helloworld /opt
Above example won’t follow any symbolic link. If you want to search symbolic link to then run the following command.
grep -R helloworld /opt
Grep Multiple Strings
We are searching the file for the words hello, hi, world in the omgfoss.txt file:
grep ‘hello\|hi\|world’ /etc/omgfoss.txt
Grep Show Only Filename
Below is the example to search through all files ending with .txt in the current directory where you are right now and print only the files name containing the string heloworld type:
grep -l helloworld *.txt
This much for now. This tutorial is intended for beginner level of Linux users. Please let us know if there is any error in this post.