Include the full path to the file and it will work provided your script (generally user nobody) has sufficient rights. ALWAYS check your return values and you will ALWAYS (almost ;-) know why things don't work if they fail....

my $fullpath = $webserver.$path.$to.$file;

unlink $fullpath 
    or dienice("Can't unline '$fullpath' Perl says the error is $!");

# with CGI let's avoid a 500 error
sub dienice {
    print "Content-type: text/html\n\n" . shift;
}
[download]

You also have typo's in your post that will stop it working FWIW

tachyon

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