Particularly if the filename is determined from the
command line, you want to do as
perlsyn says and put
an error check on the
open which specifies all of the
following:
- What you were doing.
- What the filename is.
- The contents of $!.
In this particular case I think it is also probably
worthwhile to have a usage check to inform the user if
they call the script with an invalid argument. The
obvious alternative is to insert a question in the
die which asks them if they called it with the argument
that they were supposed to.
There are very few ideas that I consider more important
in writing useful code than trying to make your code
debuggable when things go wrong...