How about using the standard Unix utility 'file' or even the Perl module File::Type.

use warnings;
use strict;

my @Progs = ('gzip', 'bzip2');

my $File = <STDIN>;

foreach (@Progs) {
        my $Output = `file $File`;
        chomp $Output;
        `$_ -d $File` if ($Output =~ $_);
}
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I tried to have a look at File::Type also but during the install it spat lots of errors so I didn't go any further.

CC