I'll just jump in and promote the use of autodie, a module that takes care of catching file open errors. For quite a while I wrote file operations in C like this:

  FILE *pif;
  pif = fopen ( $filename, 'r' );
  if ( pif == NULL ) {

    /* Problem opening file.. */
  }
  ..
  fclose ( pif );
[download]

When I started writing Perl, I did the same kind of thing ..

  open ( my $in_fh, '<', $filename ) or
    die "Unable to open $filename for read: $!";
  ..
  close ( $in_fh );
[download]

With autodie, that can be simplified to

  use autodie;
  open ( my $in_fh, '<', $filename );
  ..
  close ( $in_fh );
[download]

I think that's pretty handy.