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File::Which(3)        User Contributed Perl Documentation       File::Which(3)
NAME
       File::Which - Perl implementation of the which utility as an API
VERSION
       version 1.22
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 finds the full or relative paths to executable programs on
       the system.  This is normally the function of "which" utility.  "which"
       is typically implemented as either a program or a built in shell
       command.  On some platforms, such as Microsoft Windows it is not
       provided as part of the core operating system.  This module provides a
       consistent API to this functionality regardless of the underlying
       platform.
       The focus of this module is correctness and portability.  As a
       consequence platforms where the current directory is implicitly part of
       the search path such as Microsoft Windows will find executables in the
       current directory, whereas on platforms such as UNIX where this is not
       the case executables in the current directory will only be found if the
       current directory is explicitly added to the path.
       If you need a portable "which" on the command line in an environment
       that does not provide it, install App::pwhich which provides a command
       line interface to this API.
   Implementations
       File::Which searches the directories of the user's "PATH" (the current
       implementation uses File::Spec#path to determine the correct "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.)
       Linux, *BSD and other UNIXes
       There should not be any surprises here.  The current directory will not
       be searched unless it is explicitly added to the path.
       Modern Windows (including NT, XP, Vista, 7, 8, 10 etc)
       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.
       Cygwin
       Cygwin provides a Unix-like environment for Microsoft Windows users.
       In most ways it works like other Unix and Unix-like environments, but
       in a few key aspects it works like Windows.  As with other Unix
       environments, the current directory is not included in the search
       unless it is explicitly included in the search path.  Like on Windows,
       files with ".EXE" or <.BAT> extensions will be discovered even if they
       are not part of the query.  ".COM" or extensions specified using the
       "PATHEXT" environment variable will NOT be discovered without the fully
       qualified name, however.
       Windows 95, 98, ME, MS-DOS, OS/2
       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.
       As of 2015 none of these platforms are tested frequently (or perhaps
       ever), but the current maintainer is determined not to intentionally
       remove support for older operating systems.
       VMS
       Same case as Windows 9x: uses ".exe" and ".com" (in that order).
       As of 2015 the current maintainer does not test on VMS, and is in fact
       not certain it has ever been tested on VMS.  If this platform is
       important to you and you can help me verify and or support it on that
       platform please contact me.
FUNCTIONS
   which
        my $path = which $short_exe_name;
        my @paths = 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
        my @paths = where $short_exe_name;
       Not exported by default.
       Same as "which" in array context. Same as the "where" utility, will
       return an array containing all the path names matching $short_exe_name.
CAVEATS
       This module has no non-core requirements for Perl 5.6.2 and better.
       This module is fully supported back to Perl 5.8.1.  It may work on
       5.8.0.  It should work on Perl 5.6.x and I may even test on 5.6.2.  I
       will accept patches to maintain compatibility for such older Perls, but
       you may need to fix it on 5.6.x / 5.8.0 and send me a patch.
       Not tested on VMS 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.
SUPPORT
       Bugs should be reported via the GitHub issue tracker
       <https://github.com/plicease/File-Which/issues>;
       For other issues, contact the maintainer.
SEE ALSO
       pwhich, App::pwhich
           Command line interface to this module.
       IPC::Cmd
           Comes with a "can_run" function with slightly different semantics
           that the traditional UNIX where.  It will find executables in the
           current directory, even though the current directory is not
           searched for by default on Unix.
       Devel::CheckBin
           This module purports to "check that a command is available", but
           does not provide any documentation on how you might use it.
AUTHORS
       o   Per Einar Ellefsen <pereinar AT cpan.org>
       o   Adam Kennedy <adamk AT cpan.org>
       o   Graham Ollis <plicease AT cpan.org>
COPYRIGHT AND LICENSE
       This software is copyright (c) 2002 by Per Einar Ellefsen
       <pereinar AT cpan.org>.
       This is free software; you can redistribute it and/or modify it under
       the same terms as the Perl 5 programming language system itself.
perl v5.26.3                      2017-09-08                    File::Which(3)