You should include the $! variable in the error message so you know why it failed to open:
There's no need to add that to every statement for a quick script unless you do expect to run on that error often. You can figure out the error code after the fact as perl's die statement helpfully sets the exit code to $! % 256 || 1, so eg. if you print the exit code from the shell after you get this error message and you find that it's 2 you can be sure the error was ENOENT (No such file or directory). (The higher error codes are platform-dependent, but you can still find out the strerror message for them with eg. perl -we 'die($!=2)')
