grep in Bash

How do I use grep command in Bash?

The grep command searches the given files for lines containing a match to a given pattern list. In other words, use the grep command to search words or strings in a text files. When it finds a match in a file, it will display those line on screen.

grep examples in bash

The syntax is as follows:

grep 'word-to-search' filename
egrep 'word1|word2' /path/to/filename

Examples

Search for word vivek in /etc/passwd file, enter:
grep vivek /etc/passwd
Sample outputs:

vivek:x:500:100::/home/vivek:/bin/bash

Search for word vivek or priyanka in /etc/passwd file, enter:
egrep -w 'vivek|priyanka' /etc/passwd
Search all files in directory /nas/project for words 'main':
egrep -R 'main' *
OR limit search to word only
egrep -Rw 'main' *
Highlight words with color:
egrep --color -R 'main' *