The ABC's of grep - I

I

Use the -i flag to ignore case​ in the results.

Let’s return back to our handy test.txt file and add “Happy” to the end:

sad
happy
awake
coffee
work
school
Happy

To ignore case differences run:

$ grep -i "happy" test.txt
happy 
Happy

The uppercase variant is also an “ignore” flag, but this time we are ignoring binary files. So if the current directory with test.txt, also contained test.pdf, the following would ignore the pdf file:

$ grep -I "happy" *
test.txt:happy