Use of Shellscripts in Software Testing?

Dear Members

Greetings to all

I am presently working as a Software Tester, where
I may need to use Unix Shell scripting in future.
Infact, first I want to know ” How shell scripting is useful in Software Testing?”
and If I want to learn in short period, please tell me the best method to learn that.
Second one is, Can You Please send me some shellscripts which were previously used for SOftware Testing as an examples?

Looking forward for your reply

Thanks to all

Venkat