grep

Command	Description
grep strings filename	Search file for specific pattern or string
grep –i	To ignore upper/low case distinctions
grep -w	Checking for full words, not for sub-strings
grep -v	Display lines that DO NOT match the pattern
grep -n	Precede each line with the line number
grep -c	Return only the total count of matched lines
grep -r	Sets the search to “recursive”, so it will search the current directory and all subdirectories for any file that contains the pattern