The grep Command

Summary

The grep command searches any given input files, selecting lines that match one or more patterns.

It can search for specific words, phrases, or patterns inside a text file, and display the matching lines.

Basic command structure

For all descriptions below, the dollar sign indicates that BASH command prompt.

$ grep [options] pattern [file]

Possible Flags

-i

Perform case insensitive matching. By default, grep is case sensitive.

-c

Displays the number of lines that match the given pattern.

-l

Displays the files that contain the given pattern.

-v

Displays the the lines that do not match the given pattern.

Output Examples

The grep command has many different kinds of outputs as described below:

• Standard output with no flags, which displays the lines containing the word, phrase, or pattern:

• Output with -c flag, which displays the number of lines containing the word, phrase, or pattern:

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