if (!-e $file) {
   die "'$file' does not exists';
}
if (!-r $file) {
   die "insufficient permissions to read `$file'";
}
if (-d $file) {
   die "`$file' is a directory, not a plain file";
}
# and so on

##</code><code>##

open my $handle, '<', $file or die "Can't open `$fil'e for reading: $!"