in reply to Re^2: How to test if a file is gzipped or not
in thread How to test if a file is gzipped or not

There's also File::MMagic and File::Type, and many more.

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

In Section Seekers of Perl Wisdom