Re: opened file being overwritten

[GrandFather]

This is a good time to start always using the three parameter version of open and lexical file handles:

open my $file4In, '<', $fileName or die "Could not open $filename: $!\
+n";

Appending In or Out to your file handles helps as a sanity and consistency check.

You get even more linty goodness if you always use strictures (use strict; use warnings;).

Note too that showing why an open failed often is at least as useful as showing which open failed.

[davido]

I might add that while it's uncommon to see it done here, checking the return value of print can be useful. Consider this:

perl -e 'print BADHANDLE "Hello world.\n" or die $!'

...output...

Bad file descriptor at -e line 1.

...which is kinda nice information to know.