http://www.perlmonks.org?node_id=11120471


in reply to Re^2: Should I worry about "Inappropriate ioctl for device"?
in thread Should I worry about "Inappropriate ioctl for device"?

If you use it just in the messages coming from die or warn, it's confusing, but not critical. Basing the program flow on the value would be a critical problem, though:
... die $! if $!; # Can stop your program for no real reason.
map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]