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
<
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=File-Which>
For other issues, contact the maintainer.
AUTHOR¶
Adam Kennedy <adamk@cpan.org>
Per Einar Ellefsen <pereinar@cpan.org>
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>.