Rather than try to juggle files and paths yourself, you could employ the File::Basename and File::Spec core modules to do the heavy lifting. They have the advantage of being portable and well-tested. I have written a script which I think is doing what you are after but I use those modules to manipulate the paths and I use regular expressions with captures (see perlretut, perlre and perlreref) rather than your split.

use strict;
use warnings;

use Cwd qw{ abs_path };
use File::Basename;
use File::Spec;

my $scriptPath = abs_path( $0 );

my $path = ( fileparse( $scriptPath ) )[ 1 ];

my $configFileName = File::Spec->catfile( $path, q{spw750353.ini} );
open my $configFH, q{<}, $configFileName
   or die qq{open: < $configFileName: $!\n};

my $fileFromConfig = q{};
my $pathFromConfig = q{};
while( <$configFH> )
{
    if( m{^myfile=(.+)} )
    {
        $fileFromConfig = $1;
    }
    elsif( m{^path=(.+)} )
    {
        $pathFromConfig = $1;
    }
    else
    {
        warn qq{$_ : line not recognised\n};
    }
}

close $configFH
   or die qq{close: < $configFileName: $!\n};

my $fullPath =
   File::Spec->catfile( $pathFromConfig, $fileFromConfig );
print qq{$fullPath\n};
[download]

Here is the .ini file, shown both from the Cygwin (*nix-like) environment and from the command prompt under Windows XP.

$ cat spw750353.ini 
myfile=bbbbbbb.txt
path=aaaaaaaaaaaaaaa
$
[download]

C:\cygwin\home\johngg\perl\Monks>type spw750353.ini
myfile=bbbbbbb.txt
path=aaaaaaaaaaaaaaa

C:\cygwin\home\johngg\perl\Monks>
[download]

Here is the script running unaltered in both environments.

$ ./spw750353
aaaaaaaaaaaaaaa/bbbbbbb.txt

$
[download]

C:\cygwin\home\johngg\perl\Monks>perl spw750353
aaaaaaaaaaaaaaa\bbbbbbb.txt

C:\cygwin\home\johngg\perl\Monks>
[download]

Note how the modules use the path separator appropriate to the environment without programmer intervention.

I hope this is helpful.

Cheers,

JohnGG