lib/perl5/5.8.8/FindBin.pm

   1 # FindBin.pm
   2 #
   3 # Copyright (c) 1995 Graham Barr & Nick Ing-Simmons. All rights reserved.
   4 # This program is free software; you can redistribute it and/or modify it
   5 # under the same terms as Perl itself.
   6
   7 =head1 NAME
   8
   9 FindBin - Locate directory of original perl script
  10
  11 =head1 SYNOPSIS
  12
  13  use FindBin;
  14  use lib "$FindBin::Bin/../lib";
  15
  16  or
  17
  18  use FindBin qw($Bin);
  19  use lib "$Bin/../lib";
  20
  21 =head1 DESCRIPTION
  22
  23 Locates the full path to the script bin directory to allow the use
  24 of paths relative to the bin directory.
  25
  26 This allows a user to setup a directory tree for some software with
  27 directories C<< <root>/bin >> and C<< <root>/lib >>, and then the above
  28 example will allow the use of modules in the lib directory without knowing
  29 where the software tree is installed.
  30
  31 If perl is invoked using the B<-e> option or the perl script is read from
  32 C<STDIN> then FindBin sets both C<$Bin> and C<$RealBin> to the current
  33 directory.
  34
  35 =head1 EXPORTABLE VARIABLES
  36
  37  $Bin         - path to bin directory from where script was invoked
  38  $Script      - basename of script from which perl was invoked
  39  $RealBin     - $Bin with all links resolved
  40  $RealScript  - $Script with all links resolved
  41
  42 =head1 KNOWN ISSUES
  43
  44 If there are two modules using C<FindBin> from different directories
  45 under the same interpreter, this won't work. Since C<FindBin> uses a
  46 C<BEGIN> block, it'll be executed only once, and only the first caller
  47 will get it right. This is a problem under mod_perl and other persistent
  48 Perl environments, where you shouldn't use this module. Which also means
  49 that you should avoid using C<FindBin> in modules that you plan to put
  50 on CPAN. To make sure that C<FindBin> will work is to call the C<again>
  51 function:
  52
  53   use FindBin;
  54   FindBin::again(); # or FindBin->again;
  55
  56 In former versions of FindBin there was no C<again> function. The
  57 workaround was to force the C<BEGIN> block to be executed again:
  58
  59   delete $INC{'FindBin.pm'};
  60   require FindBin;
  61
  62 =head1 KNOWN BUGS
  63
  64 If perl is invoked as
  65
  66    perl filename
  67
  68 and I<filename> does not have executable rights and a program called
  69 I<filename> exists in the users C<$ENV{PATH}> which satisfies both B<-x>
  70 and B<-T> then FindBin assumes that it was invoked via the
  71 C<$ENV{PATH}>.
  72
  73 Workaround is to invoke perl as
  74
  75  perl ./filename
  76
  77 =head1 AUTHORS
  78
  79 FindBin is supported as part of the core perl distribution. Please send bug
  80 reports to E<lt>F<perlbug@perl.org>E<gt> using the perlbug program
  81 included with perl.
  82
  83 Graham Barr E<lt>F<gbarr@pobox.com>E<gt>
  84 Nick Ing-Simmons E<lt>F<nik@tiuk.ti.com>E<gt>
  85
  86 =head1 COPYRIGHT
  87
  88 Copyright (c) 1995 Graham Barr & Nick Ing-Simmons. All rights reserved.
  89 This program is free software; you can redistribute it and/or modify it
  90 under the same terms as Perl itself.
  91
  92 =cut
  93
  94 package FindBin;
  95 use Carp;
  96 require 5.000;
  97 require Exporter;
  98 use Cwd qw(getcwd cwd abs_path);
  99 use Config;
 100 use File::Basename;
 101 use File::Spec;
 102
 103 @EXPORT_OK = qw($Bin $Script $RealBin $RealScript $Dir $RealDir);
 104 %EXPORT_TAGS = (ALL => [qw($Bin $Script $RealBin $RealScript $Dir $RealDir)]);
 105 @ISA = qw(Exporter);
 106
 107 $VERSION = "1.47";
 108
 109 sub cwd2 {
 110    my $cwd = getcwd();
 111    # getcwd might fail if it hasn't access to the current directory.
 112    # try harder.
 113    defined $cwd or $cwd = cwd();
 114    $cwd;
 115 }
 116
 117 sub init
 118 {
 119  *Dir = \$Bin;
 120  *RealDir = \$RealBin;
 121
 122  if($0 eq '-e' || $0 eq '-')
 123   {
 124    # perl invoked with -e or script is on C<STDIN>
 125    $Script = $RealScript = $0;
 126    $Bin    = $RealBin    = cwd2();
 127   }
 128  else
 129   {
 130    my $script = $0;
 131
 132    if ($^O eq 'VMS')
 133     {
 134      ($Bin,$Script) = VMS::Filespec::rmsexpand($0) =~ /(.*\])(.*)/s;
 135      ($RealBin,$RealScript) = ($Bin,$Script);
 136     }
 137    else
 138     {
 139      my $dosish = ($^O eq 'MSWin32' or $^O eq 'os2');
 140      unless(($script =~ m#/# || ($dosish && $script =~ m#\\#))
 141             && -f $script)
 142       {
 143        my $dir;
 144        foreach $dir (File::Spec->path)
 145         {
 146         my $scr = File::Spec->catfile($dir, $script);
 147         if(-r $scr && (!$dosish || -x _))
 148          {
 149           $script = $scr;
 150
 151           if (-f $0)
 152            {
 153             # $script has been found via PATH but perl could have
 154             # been invoked as 'perl file'. Do a dumb check to see
 155             # if $script is a perl program, if not then $script = $0
 156             #
 157             # well we actually only check that it is an ASCII file
 158             # we know its executable so it is probably a script
 159             # of some sort.
 160
 161             $script = $0 unless(-T $script);
 162            }
 163           last;
 164          }
 165        }
 166      }
 167
 168      croak("Cannot find current script '$0'") unless(-f $script);
 169
 170      # Ensure $script contains the complete path in case we C<chdir>
 171
 172      $script = File::Spec->catfile(cwd2(), $script)
 173        unless File::Spec->file_name_is_absolute($script);
 174
 175      ($Script,$Bin) = fileparse($script);
 176
 177      # Resolve $script if it is a link
 178      while(1)
 179       {
 180        my $linktext = readlink($script);
 181
 182        ($RealScript,$RealBin) = fileparse($script);
 183        last unless defined $linktext;
 184
 185        $script = (File::Spec->file_name_is_absolute($linktext))
 186                   ? $linktext
 187                   : File::Spec->catfile($RealBin, $linktext);
 188       }
 189
 190      # Get absolute paths to directories
 191      if ($Bin) {
 192       my $BinOld = $Bin;
 193       $Bin = abs_path($Bin);
 194       defined $Bin or $Bin = File::Spec->canonpath($BinOld);
 195      }
 196      $RealBin = abs_path($RealBin) if($RealBin);
 197     }
 198   }
 199 }
 200
 201 BEGIN { init }
 202
 203 *again = \&init;
 204
 205 1; # Keep require happy