The which utility takes a list of command names and searches the path for each executable file that would be run had these commands actually been invoked.

The following options are available:

• -a List all instances of executables found (instead of just the first one of each).
• -s No output, just return 0 if all of the executables are found, or 1 if some were not found.

Some shells may provide a builtin which command which is similar or identical to this utility. Consult the builtin(1) manual page.

builtin(1), csh(1), find(1), locate(1), whereis(1)

The which command first appeared in

The which utility was originally written in Perl and was contributed by The current version of which was rewritten in C by