Linux's various search commands find, whereis...

find is the most powerful, it can check everything,

which can only check executable files

, whereis can only check binary files, documentation, source files, etc.

locate can check everything, but like whereis, it checks the contents of the database.

which can only look for executable files and in the PATH variable.

whereis looks from the linux file database (/var/lib/slocate/slocate.db), so it is possible to find files that were just deleted, or not newly created.

locate Same as above, but with partial filename matches.

find is to search directly on the hard disk. It has powerful functions, but it consumes hard disk and is generally not used.