- Using typeglobs for filehandles (like
OUT
) is not a good idea, as they are global across your entire program – you need to be sure that no other routine including those in modules are using the same name (including in the future). - Using the two-argument form of open exposes your application to mis-behaviour caused by variables containing special characters, for example
my $f; open $f, ">$some_filename";
is exposed to the bug where$some_filename
containing a leading>
will change the program’s behaviour.
Using the three-argument form avoids this by separating the mode and filename into separate arguments where they can’t interfere.
Moreover, using the lots-of-arguments form with pipes is a very good idea:
open $pipe, '|-', 'sendmail', '[email protected]';
Is better than doing it all as a single string – it avoids possible shell injection etc.