Case Insensitive Grep Search

To perform a grep search that ignores case, or is case insensitive, use the -i option (or --ignore-case). The grep command is case sensitive by default.

Example Grep Case Insensitive

grep -i bob grep-example-file.txt

The above command will use the grep executable to search the file file.txt for the string bob. It will return each line of the file that contains the word string bob no matter if it is spelled with upper case or lower case letters.

Grep Example File

Here's the contents of the file used in the case insensitive grep search above: grep-example-file.txt

Bob always ignores case.
Is bob your name?
This line does not have what you want in any case.
BOB

Results of grep --ignore-case bob grep-example-file.txt

Here we are going to use the longer, but more descriptive grep command line argument --ignore-case to accomplish the same task as above:

grep --ignore-case bob file.txt

Which outputs the lines:

Bob always ignores case.
Is bob your name?
BOB

As you can see both options will solve our task equally well to perform a case insensitive grep file search. The -i and --ignore-case grep options should exist on Mac and Linux servers (Ubuntu, RedHat, Amazon, etc)