An easier way to get rid of the path is:

use File::Basename;
my $iam = basename $0;
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I used to use a regex substitution instead, and my fingers still "remember" the sequence: (my $iam = $0) =~ s,.*/,,;

But when I started coding in Perl for Windows in addition to (Li|U)n[ui]x, it was unwieldy to use a regex which accounted for all the different pathname symbols.  Someone told me about the File::Basename method, and I've used it ever since; it's easier to remember, easier to type, and part of the standard Perl distro on both systems.