.\" Manpage Copyright (c) 1995, Jordan Hubbard <jkh@FreeBSD.org>
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"      This product includes software developed by the FreeBSD Project
.\"      its contributors.
.\" 4. Neither the name of the FreeBSD Project nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE CONTRIBUTOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
.\" OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd September 24, 2020
.Dt WHICH 1
.Os
.Sh NAME
.Nm which
.Nd "locate a program file in the user's path"
.Sh SYNOPSIS
.Nm
.Op Fl as
.Ar program ...
.Sh DESCRIPTION
The
.Nm
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.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl a
List all instances of executables found (instead of just the first one
of each).
.It Fl s
No output, just return 0 if all of the executables are found, or 1 if
some were not found.
.El
.Pp
Some shells may provide a builtin
.Nm
command which is similar or identical to this utility.
Consult the
.Xr builtin 1
manual page.
.Sh EXAMPLES
Locate the
.Xr ls 1
and
.Xr cp 1
commands:
.Bd -literal -offset indent
$ /usr/bin/which ls cp
/bin/ls
/bin/cp
.Ed
.Pp
Same as above with a specific
.Ev PATH
and showing all occurrences:
.Bd -literal -offset indent
$ PATH=/bin:/rescue /usr/bin/which -a ls cp
/bin/ls
/rescue/ls
/bin/cp
/rescue/cp
.Ed
.Pp
.Nm which
will show duplicates if the same executable is found more than once:
.Bd -literal -offset indent
$ PATH=/bin:/bin /usr/bin/which -a ls
/bin/ls
/bin/ls
.Ed
.Pp
Do not show output.
Just exit with an appropriate return code:
.Bd -literal -offset indent
$ /usr/bin/which -s ls cp
$ echo $?
0

$ /usr/bin/which -s fakecommand
$ echo $?
1
.Ed
.Sh SEE ALSO
.Xr builtin 1 ,
.Xr csh 1 ,
.Xr find 1 ,
.Xr locate 1 ,
.Xr whereis 1
.Sh HISTORY
The
.Nm
command first appeared in
.Fx 2.1 .
.Sh AUTHORS
.An -nosplit
The
.Nm
utility was originally written in Perl and was contributed by
.An Wolfram Schneider Aq Mt wosch@FreeBSD.org .
The current version of
.Nm
was rewritten in C by
.An Daniel Papasian Aq Mt dpapasia@andrew.cmu.edu .