Grep command series: Use the grep command to search for multiple words

Grep command series: Use the grep command to search for multiple words

How can we use the grep command to search for multiple strings or words? For example, if I want to search for word1, word2, word3, and other words in the/path/to/file, how can I run grep to search for these words?

The grep command supports regular expression matching. To use multi-word search, use the following syntax:

1. grep'word1\|word2\|word3'/path/to/file

In the following example, search for the words warning, error, and critical in a text log file named/var/log/messages, and enter:

1. $ grep'warning\|error\|critical'/var/log/messages

You can add the-w option parameter to match a word (that is, if the word is separated by spaces in the west:

1. $ grep-w'warning\|error\|critical'/var/log/messages

The egrep command can skip the preceding syntax format. The syntax format is as follows:

1. $ egrep -w'warning|error|critical'/var/log/messages

I recommend that you add the-I (case-insensitive) and -- color options, as shown below:

1. $ egrep -wi --color 'warning|error|critical'/var/log/messages

Output example:

Fig.01: Linux/Unix egrep Command Search Multiple Words Demo Output

Figure 1: Linux/Unix egrep command to find multiple word output examples

Grep uses concise and Regular Expressions

Regular Expression usage

Assertion with Zero Width of a regular expression

Linux Command-grep for file text operations

Grep Regular Expression

Regular Expressions and file formatting commands in Linux (awk/grep/sed)

Via: http://www.cyberciti.biz/faq/searching-multiple-words-string-using-grep/

Author: Vivek Gite Translator: runningwater Proofreader: wxy

This article was originally compiled by LCTT and launched with the honor of Linux in China

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