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package File::Which;
use 5.004;
use strict;
use Exporter ();
use File::Spec ();
use vars qw{$VERSION @ISA @EXPORT @EXPORT_OK};
BEGIN {
$VERSION = '1.09';
@ISA = 'Exporter';
@EXPORT = 'which';
@EXPORT_OK = 'where';
}
use constant IS_VMS => ($^O eq 'VMS');
use constant IS_MAC => ($^O eq 'MacOS');
use constant IS_DOS => ($^O eq 'MSWin32' or $^O eq 'dos' or $^O eq 'os2');
# For Win32 systems, stores the extensions used for
# executable files
# For others, the empty string is used
# because 'perl' . '' eq 'perl' => easier
my @PATHEXT = ('');
if ( IS_DOS ) {
# WinNT. PATHEXT might be set on Cygwin, but not used.
if ( $ENV{PATHEXT} ) {
push @PATHEXT, split ';', $ENV{PATHEXT};
} else {
# Win9X or other: doesn't have PATHEXT, so needs hardcoded.
push @PATHEXT, qw{.com .exe .bat};
}
} elsif ( IS_VMS ) {
push @PATHEXT, qw{.exe .com};
}
sub which {
my ($exec) = @_;
return undef unless $exec;
my $all = wantarray;
my @results = ();
# check for aliases first
if ( IS_VMS ) {
my $symbol = `SHOW SYMBOL $exec`;
chomp($symbol);
unless ( $? ) {
return $symbol unless $all;
push @results, $symbol;
}
}
if ( IS_MAC ) {
my @aliases = split /\,/, $ENV{Aliases};
foreach my $alias ( @aliases ) {
# This has not been tested!!
# PPT which says MPW-Perl cannot resolve `Alias $alias`,
# let's just hope it's fixed
if ( lc($alias) eq lc($exec) ) {
chomp(my $file = `Alias $alias`);
last unless $file; # if it failed, just go on the normal way
return $file unless $all;
push @results, $file;
# we can stop this loop as if it finds more aliases matching,
# it'll just be the same result anyway
last;
}
}
}
my @path = File::Spec->path;
if ( IS_DOS or IS_VMS or IS_MAC ) {
unshift @path, File::Spec->curdir;
}
foreach my $base ( map { File::Spec->catfile($_, $exec) } @path ) {
for my $ext ( @PATHEXT ) {
my $file = $base.$ext;
# We don't want dirs (as they are -x)
next if -d $file;
if (
# Executable, normal case
-x _
or (
# MacOS doesn't mark as executable so we check -e
IS_MAC
||
(
IS_DOS
and
grep {
$file =~ /$_\z/i
} @PATHEXT[1..$#PATHEXT]
)
# DOSish systems don't pass -x on
# non-exe/bat/com files. so we check -e.
# However, we don't want to pass -e on files
# that aren't in PATHEXT, like README.
and -e _
)
) {
return $file unless $all;
push @results, $file;
}
}
}
if ( $all ) {
return @results;
} else {
return undef;
}
}
sub where {
# force wantarray
my @res = which($_[0]);
return @res;
}
1;
__END__
=pod
=head1 NAME
File::Which - Portable implementation of the `which' utility
=head1 SYNOPSIS
use File::Which; # exports which()
use File::Which qw(which where); # exports which() and where()
my $exe_path = which('perldoc');
my @paths = where('perl');
- Or -
my @paths = which('perl'); # an array forces search for all of them
=head1 DESCRIPTION
C<File::Which> was created to be able to get the paths to executable programs
on systems under which the `which' program wasn't implemented in the shell.
C<File::Which> searches the directories of the user's C<PATH> (as returned by
C<File::Spec-E<gt>path()>), looking for executable files having the name
specified as a parameter to C<which()>. Under Win32 systems, which do not have a
notion of directly executable files, but uses special extensions such as C<.exe>
and C<.bat> to identify them, C<File::Which> takes extra steps to assure that
you will find the correct file (so for example, you might be searching for
C<perl>, it'll try F<perl.exe>, F<perl.bat>, etc.)
=head1 Steps Used on Win32, DOS, OS2 and VMS
=head2 Windows NT
Windows NT has a special environment variable called C<PATHEXT>, which is used
by the shell to look for executable files. Usually, it will contain a list in
the form C<.EXE;.BAT;.COM;.JS;.VBS> etc. If C<File::Which> finds such an
environment variable, it parses the list and uses it as the different
extensions.
=head2 Windows 9x and other ancient Win/DOS/OS2
This set of operating systems don't have the C<PATHEXT> variable, and usually
you will find executable files there with the extensions C<.exe>, C<.bat> and
(less likely) C<.com>. C<File::Which> uses this hardcoded list if it's running
under Win32 but does not find a C<PATHEXT> variable.
=head2 VMS
Same case as Windows 9x: uses C<.exe> and C<.com> (in that order).
=head1 Functions
=head2 which($short_exe_name)
Exported by default.
C<$short_exe_name> is the name used in the shell to call the program (for
example, C<perl>).
If it finds an executable with the name you specified, C<which()> will return
the absolute path leading to this executable (for example, F</usr/bin/perl> or
F<C:\Perl\Bin\perl.exe>).
If it does I<not> find the executable, it returns C<undef>.
If C<which()> is called in list context, it will return I<all> the
matches.
=head2 where($short_exe_name)
Not exported by default.
Same as C<which($short_exe_name)> in array context. Same as the
C<`where'> utility, will return an array containing all the path names
matching C<$short_exe_name>.
=head1 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?
=head1 SUPPORT
Bugs should be reported via the CPAN bug tracker at
L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=File-Which>
For other issues, contact the maintainer.
=head1 AUTHOR
Adam Kennedy E<lt>adamk@cpan.orgE<gt>
Per Einar Ellefsen E<lt>pereinar@cpan.orgE<gt>
Originated in F<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 C<File::Which>.
Version 0.04 had some significant platform-related changes, taken from
the Perl Power Tools C<`which'> implementation by Abigail with
enhancements from Peter Prymmer. See
L<http://www.perl.com/language/ppt/src/which/index.html> for more
information.
=head1 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.
=head1 SEE ALSO
L<File::Spec>, L<which(1)>, Perl Power Tools:
L<http://www.perl.com/language/ppt/index.html>.
=cut
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