NAME
File::Which - Portable implementation of the `which' utility
SYNOPSIS
use File::Which; # exports which()
use File::Which qw(which where); # exports which() and where()
my $exe_path = which('perldoc');
my @paths = where('perl');
- Or -
my @paths = which('perl'); # an array forces search for all of them
DESCRIPTION
"File::Which" was created to be able to get the paths to executable
programs on systems under which the `which' program wasn't implemented
in the shell.
"File::Which" searches the directories of the user's "PATH" (as returned
by "File::Spec->path()"), looking for executable files having the name
specified as a parameter to "which()". Under Win32 systems, which do not
have a notion of directly executable files, but uses special extensions
such as ".exe" and ".bat" to identify them, "File::Which" takes extra
steps to assure that you will find the correct file (so for example, you
might be searching for "perl", it'll try perl.exe, perl.bat, etc.)
Steps Used on Win32, DOS, OS2 and VMS
Windows NT
Windows NT has a special environment variable called "PATHEXT", which is
used by the shell to look for executable files. Usually, it will contain
a list in the form ".EXE;.BAT;.COM;.JS;.VBS" etc. If "File::Which" finds
such an environment variable, it parses the list and uses it as the
different extensions.
Windows 9x and other ancient Win/DOS/OS2
This set of operating systems don't have the "PATHEXT" variable, and
usually you will find executable files there with the extensions ".exe",
".bat" and (less likely) ".com". "File::Which" uses this hardcoded list
if it's running under Win32 but does not find a "PATHEXT" variable.
VMS
Same case as Windows 9x: uses ".exe" and ".com" (in that order).
Functions
which($short_exe_name)
Exported by default.
$short_exe_name is the name used in the shell to call the program (for
example, "perl").
If it finds an executable with the name you specified, "which()" will
return the absolute path leading to this executable (for example,
/usr/bin/perl or C:\Perl\Bin\perl.exe).
If it does *not* find the executable, it returns "undef".
If "which()" is called in list context, it will return *all* the
matches.
where($short_exe_name)
Not exported by default.
Same as "which($short_exe_name)" in array context. Same as the `where'
utility, will return an array containing all the path names matching
$short_exe_name.
BUGS AND CAVEATS
Not tested on VMS or MacOS, although there is platform specific code for
those. Anyone who haves a second would be very kind to send me a report
of how it went.
File::Spec adds the current directory to the front of PATH if on Win32,
VMS or MacOS. I have no knowledge of those so don't know if the current
directory is searced first or not. Could someone please tell me?
SUPPORT
Bugs should be reported via the CPAN bug tracker at
<
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=File-Which>
For other issues, contact the maintainer.
AUTHOR
Adam Kennedy <
[email protected]>
Per Einar Ellefsen <
[email protected]>
Originated in modperl-2.0/lib/Apache/Build.pm. Changed for use in DocSet
(for the mod_perl site) and Win32-awareness by me, with slight
modifications by Stas Bekman, then extracted to create "File::Which".
Version 0.04 had some significant platform-related changes, taken from
the Perl Power Tools `which' implementation by Abigail with enhancements
from Peter Prymmer. See
<
http://www.perl.com/language/ppt/src/which/index.html> for more
information.
COPYRIGHT
Copyright 2002 Per Einar Ellefsen.
Some parts copyright 2009 Adam Kennedy.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
SEE ALSO
File::Spec, which(1), Perl Power Tools:
<
http://www.perl.com/language/ppt/index.html>.
