You can usually assume that your libraries are in some fixed place relative to the script path which you can find as $0.

Example: 

# untested!
use File::Spec;
BEGIN {
    my $script = File::Spec->rel2abs($0);
    my ($drive, $dir) = File::Spec->splitpath($script);
    my $base = File::Spec->catpath($drive, $dir);
    if ($^O eq 'MSWin32') {
        push @INC, "$base\\lib";
    }
    else {
        push @INC, "$base/../lib";
    }
}

[download]
You just have to ensure that your Perl applications are installed using the fixed directory structure matching your code expectations.

Update: Also, on Windows you may like to store the path to your application on the registry when it is installed.

In reply to Re^5: standard library to return system paths by salva
in thread standard library to return system paths by igoryonya

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