I am a student of BSc. in IT from Calcutta(INDIA). I need your help.

I have a file that I need to parse, line by line in a bash
shell on Unix. I need to check the first three charcters of the line and
based on a certain value, I will keep or disregard that line. Is there any
easy way to do so ?

Any help in this regard will be highly appreciated.

Vijay Bhatter