/ 
File-Which-0.03
River stage four • 431 direct dependents • 4082 total dependents
/ File::Which

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', {all => 1 });

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

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

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.

Functions

which($short_exe_name, \%opt)

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 $ENV{HOME} is present, File::Which will expand all instances of '~' in the PATH, replacing them with the value of $ENV{HOME}. However, this will not occur on Win32, as the shell doesn't treat it specially there.

which() also accepts a hash reference with options:

  • all: if set to 1, which() will return a list of all the executable paths it finds, and not just the first match. See where().

where($short_exe_name)

Not exported by default.

Same as which($short_exe_name, { all => 1 }). Same as the `where' utility, will return an array containing all the path names matching $short_exe_name.

Bugs

Has not been tested under MacOS. If anyone could give me the information needed for it to work on the Mac (how it searches the path, etc... although MacOs < X don't have a shell, so this might not really apply).

Author

Per Einar Ellefsen, <per.einar (at) skynet.be>

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.

License

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See Also

File::Spec.