Search Multiple Words or String Pattern

Search is the most important factor which we often used in our daily routine. Some time we need to search multiple words or string in a file, and grep provides the functionality to look into a file and search more than one words.

With the combination of grep command and regular expression we can search multiple words. Syntax for searching such combination is as follow:

grep 'word1\|word2\|word3' 

Below are the common examples of grep which we uses daily:

1. Search with words in any text file:

$ grep  ‘restart\|reboot\|shutdown’  /var/log/messages

2. Grep currently running processes:

$ ps aux | grep ‘httpd\|exim\|named’

3. For exact match use the –w option:

$ grep  -w ‘restart\|reboot\|shutdown’  /var/log/messages

The same can also achieved with the egrep command. Below are the examples:

$ egrep  ‘restart|reboot|shutdown’  /var/log/messages

If you findany difficulty in using this command, please let us know.