<s>
In	O
computing	O
,	O
which	O
is	O
a	O
command	B-Device
for	O
various	O
operating	B-General_Concept
systems	I-General_Concept
used	O
to	O
identify	O
the	O
location	O
of	O
executables	B-Application
.	O
</s>
<s>
The	O
command	B-Device
is	O
available	O
in	O
Unix	B-Application
and	O
Unix-like	B-Operating_System
systems	I-Operating_System
,	O
the	O
AROS	B-Application
shell	B-Application
,	O
for	O
FreeDOS	B-Application
and	O
for	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
The	O
functionality	O
of	O
the	O
which	O
command	B-Device
is	O
similar	O
to	O
some	O
implementations	O
of	O
the	O
type	B-Device
command	B-Device
.	O
</s>
<s>
POSIX	O
specifies	O
a	O
command	B-Device
named	O
command	B-Device
that	O
also	O
covers	O
this	O
functionality	O
.	O
</s>
<s>
The	O
command	B-Device
takes	O
one	O
or	O
more	O
arguments	O
;	O
for	O
each	O
of	O
these	O
arguments	O
,	O
it	O
prints	O
the	O
full	O
path	B-Application
of	O
the	O
executable	B-Application
to	O
stdout	O
that	O
would	O
have	O
been	O
executed	O
if	O
this	O
argument	O
had	O
been	O
entered	O
into	O
the	O
shell	B-Application
.	O
</s>
<s>
It	O
does	O
this	O
by	O
searching	O
for	O
an	O
executable	B-Application
or	O
script	O
in	O
the	O
directories	O
listed	O
in	O
the	O
environment	O
variable	O
PATH	B-Application
.	O
</s>
<s>
The	O
which	O
command	B-Device
is	O
part	O
of	O
most	O
Unix-like	B-Operating_System
computers	O
.	O
</s>
<s>
It	O
is	O
also	O
part	O
of	O
the	O
C	B-Operating_System
Shell	I-Operating_System
.	O
</s>
<s>
A	O
which	O
command	B-Device
first	O
appeared	O
in	O
3BSD	O
.	O
</s>
<s>
Carlo	O
Wood	O
developed	O
the	O
GNU	B-Operating_System
implementation	O
used	O
in	O
most	O
Linux-based	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
On	O
FreeBSD	B-Operating_System
,	O
the	O
which	O
utility	O
was	O
originally	O
written	O
in	O
Perl	B-Language
by	O
Wolfram	O
Schneider	O
.	O
</s>
<s>
The	O
current	O
version	O
of	O
which	O
was	O
rewritten	O
by	O
Daniel	O
Papasian	O
using	O
the	O
C	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
The	O
command	B-Device
is	O
available	O
as	O
a	O
separate	O
package	O
for	O
Microsoft	B-Application
Windows	I-Application
as	O
part	O
of	O
the	O
GnuWin32	B-Language
project	O
and	O
the	O
UnxUtils	B-Application
collection	O
of	O
native	B-Language
Win32	B-Library
ports	O
of	O
common	O
GNU	B-Operating_System
Unix-like	B-Operating_System
utilities	O
.	O
</s>
<s>
Windows	O
also	O
includes	O
the	O
similar	O
where.exe	O
command	B-Device
.	O
</s>
<s>
The	O
same	O
functionality	O
is	O
available	O
in	O
MS-DOS	B-Application
,	O
but	O
not	O
Windows	O
,	O
as	O
the	O
built-in	O
TRUENAME	O
command	B-Device
.	O
</s>
<s>
In	O
PowerShell	B-Application
,	O
the	O
functionality	O
is	O
provided	O
by	O
the	O
Get-Command	O
Cmdlet	O
.	O
</s>
<s>
The	O
FreeDOS	B-Application
version	O
was	O
developed	O
by	O
Trane	O
Francks	O
.	O
</s>
<s>
The	O
command	B-Device
is	O
used	O
to	O
find	O
and	O
print	O
the	O
location	O
of	O
a	O
specific	O
program	O
.	O
</s>
