File::Which

Which(3)	     User Contributed Perl Documentation	     Which(3)



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 spe-
       cial extensions such as ".exe" and ".bat" to identify them,
       "File::Which" takes extra steps to assure that you will find the cor-
       rect 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 hard-
       coded 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?

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

       Originated in modperl-2.0/lib/Apache/Build.pm. Changed for use in Doc-
       Set (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 enhance-
       ments from Peter Prymmer. See http://www.perl.com/lan-
       guage/ppt/src/which/index.html for more information.

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, which(1), Perl Power Tools: http://www.perl.com/lan-
       guage/ppt/index.html .



perl v5.8.8			  2002-06-24			     Which(3)