maletin has asked for the wisdom of the Perl Monks concerning the following question:

How can I find out the absolute path of my source-code? I wrote a test-script that uses the function caller(): 

#! perl -w
# filetest.t
# should be invoked from different directories (prove -r).

use strict;
use warnings;
use Test::More tests => 2;
use File::Basename;
use File::Spec;

my $filename = (eval{caller})[1];
diag("filename of this test-script: $filename");
my $dirname = dirname( $filename );
diag("dirname of this test-script: $dirname");

my $location =
  File::Spec->catfile( $dirname, 'non-existing-file' );
diag("testing a non existing file: $location");
cmp_ok( defined -f $location, '==', 1, 'this test should fail' );

$location =
  File::Spec->catfile( $dirname, 'filetest.t' );
diag("testing an existing file: $location");
cmp_ok( defined -f $location, '==', 1, 'this file should exist' );

[download]

my output of perl lib/t/filetest.t: 

1..2
# filename of this test-script: lib/t/filetest.t
# dirname of this test-script: lib/t
# testing a non existing file: lib/t/non-existing-file
not ok 1 - this test should fail
#   Failed test 'this test should fail'
#   at lib/t/filetest.t line 19.
#          got:
#     expected: 1
# testing an existing file: lib/t/filetest.t
ok 2 - this file should exist
# Looks like you failed 1 test of 2.

[download]
How can I get the absolute filename instead of "./lib/t/filetest.t"?

Replies are listed 'Best First'.
Re: absolute pathname
by ikegami (Patriarch) on Aug 12, 2008 at 20:57 UTC
[reply]
[d/l]
      rel2abs() has problems with volumes:
      If $base is not present or ’’, then Cwd::cwd() is used. If $base is relative, then it is converted to absolute form using "rel2abs()". This means that it is taken to be relative to Cwd::cwd(). On systems with the concept of volume, if $path and $base appear to be on two different volumes, we will not attempt to resolve the two paths, and we will instead simply return $path.
[reply]

        That doesn't seem to apply to Windows. 

        D:\>perl c:script.pl
C:\path\script.pl

D:\>perl c:..\ikegami\script.pl
C:\path\script.pl

        [download]

        I could still apply to other systems, though (VMS?)

        Update: Looking at the source, it uses getdcwd (as opposed to getcwd) with the appropriate volume, returning the correct path even when different volumes are involved.

[reply]
[d/l]
[select]
Re: absolute pathname
by Lawliet (Curate) on Aug 12, 2008 at 22:57 UTC 
    use Cwd "abs_path";

my $path = abs_path($0);

    [download]

    Works for me ^^

    I'm so adjective, I verb nouns!

    chomp; # nom nom nom
[reply]
[d/l]

      thank you. here is the difference between abs_path and rel2abs(): 

      $ cd $HOME
$ ln -s /tmp softlink
$ perl softlink/mylog.pl

      [download]
      main:: path/mylog.pl (23)> abs_path=/tmp/mylog.pl
main:: path/mylog.pl (26)> rel2abs=/home/maletin/softlink/mylog.pl
MyLog::init /home/maletin/MyLog.pm (11)> INIT
MyLog::path /home/maletin/MyLog.pm (16)> /home/maletin/MyLog.pm

      [download]

      $ cat /tmp/mylog.pl 

      #! perl -w
# mylog.pl
# using a package that print it's absolute filename.

use strict;
use warnings;
use Log::Log4perl;
use Cwd qw( abs_path );
use lib $ENV{HOME};    # location of MyLog.pm
use MyLog;

my $conf = q(
log4perl.category.Log           = INFO, Screen
log4perl.appender.Screen        = Log::Log4perl::Appender::Screen
log4perl.appender.Screen.layout = Log::Log4perl::Layout::PatternLayout
log4perl.appender.Screen.layout.ConversionPattern = %l> %m %n
);

Log::Log4perl->init( \$conf );
my $log4perl_logger = Log::Log4perl->get_logger('Log');

my $abs_path = abs_path($0);
$log4perl_logger->info("abs_path=$abs_path");

my $rel2abs = File::Spec->rel2abs($0);
$log4perl_logger->info("rel2abs=$rel2abs");

MyLog->init($log4perl_logger);
MyLog->path();

      [download]

      $ cat $HOME/MyLog.pm 

      package MyLog;

use strict;
use warnings;

my $my_logger = undef;

sub init {
    my ( $class, $logger ) = @_;
    $my_logger = $logger;
    $my_logger->info('INIT');
}

sub path {
    my $path = ( eval { caller(0) } )[1];
    $my_logger->info($path);
    return $path;
}

1;

      [download]

      but because of Windows, i will use the version with "softlink" in the filename.
[reply]
[d/l]
[select]
      Not for me 
      D:\>perl c:script.pl
D:\C:script.pl

      [download]

      File::Spec::Win32's rel2abs is a wrapper around Cwd that solves this problem.

[reply]
[d/l]
[select]
Re: absolute pathname
by eyepopslikeamosquito (Archbishop) on Aug 12, 2008 at 21:28 UTC
[reply]

      It fails miserably — dies of errors — when the work directory and the script are on different volumes.

      FindBin also has other problems.

[reply]

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