Locate a program.
Syntax whereis [program ...]
The whereis utility checks the standard binary directories for the specified programs, printing out the paths of any it finds. The path searched is the string returned by the sysctl(8) utility for the user.cs_path string.
The historic flags and arguments for the whereis utility are no longer available in this version.
Show the location of the ls command:
"If I am not for myself, Who will be for me?
And if I am only for myself, What am I?
And if not now, When?" ~ Rabbi Hillel
whereis man page - Apple.com
find - Search for files that meet a desired criteria.
locate - Find files.
which - Locate a program file in the user's path.