Use the OR operator in grep to search for words and phrases

grep is a very powerful command-line search program in the Linux world. In this article, I will cover how to use OR in the grep command to search for words and phrases in a text file.

Suppose you want to find all occurrences of the words "apples" and "oranges" in the text file named fruits.txt.

$ cat fruits.txt
yellow bananas
green apples
red oranges
red apples

$ grep 'apples\|oranges' fruits.txt
green apples
red oranges
red apples

Note that you must use the backslash \ to escape the OR operator (|).

Using the OR operator, you can also search for phrases like "green apples" and "red oranges". You must escape all spaces in a phrase in addition to the OR operator.

$ grep 'green\ apples\|red\ oranges' fruits.txt
green apples
red oranges

You can get away with not escaping the spaces or the | operator if you use the extended regular expression notation.

$ grep -E 'green apples|red oranges' fruits.txt
green apples
red oranges

egrep is a variant of grep that is equivalent to grep -E.

$ egrep 'green apples|red oranges' fruits.txt
green apples
red oranges

P.S. Additional grep articles from this blog:

• Enable color output for grep
  
• Trick grep not to report itself in a search.