How to search files in unix/linux env

find PATH -name 'FILE.extn'

• find: Find is a command 
• PATH: Where do you want to search. /home will focus the search in home directory. If you are not sure about the path, mention /. This symbol stands of root. All directories will be searched including mounted filesystems.
• -name: This option makes the search case sensitive. -iname option to find something regardless of case.
• 'FILE.extn': File name that you are searching

Example:

1. find / -name 'gc.dat'
2. find /home -name 'gc.dat'
3. find / -iname 'gc.dat'