WHICH(1) General Commands Manual WHICH(1)

whichlocate a program file in the user's path

which [-as] program ...

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:

List all instances of executables found (instead of just the first one of each).
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.

Locate the ls(1) and cp(1) commands:

$ /usr/bin/which ls cp

Same as above with a specific PATH and showing all occurrences:

$ PATH=/bin:/rescue /usr/bin/which -a ls cp

which will show duplicates if the same executable is found more than once:

$ PATH=/bin:/bin /usr/bin/which -a ls

Do not show output. Just exit with an appropriate return code:

$ /usr/bin/which -s ls cp
$ echo $?

$ /usr/bin/which -s fakecommand
$ echo $?

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

The which command first appeared in FreeBSD 2.1.

The which utility was originally written in Perl and was contributed by Wolfram Schneider <wosch@FreeBSD.org>. The current version of which was rewritten in C by Daniel Papasian <dpapasia@andrew.cmu.edu>.

September 24, 2020 macOS 14.3