I have also never used this module, so the following is also a guess:

root@linux5 root# perl -W tt.pl 
(in cleanup) Can't call method "setcflag" on an undefined value at /us
+r/lib/perl5/site_perl/5.8.0/Device/SerialPort.pm line 541 during glob
+al destruction.
[download]

It appears that SerialPort.pm is looking for something to call the "setcflag" method on; furthermore it's being done "during global destruction", which makes me think it's being called during object destruction (that is, as a default destructor).

My questions would be:

* Is this all the code you have?
* Does the Device::SerialPort mention anything about the creation and destruction of Device::SerialPort objects and any called methods?
* Are you sure you need to run as root? That can be dangerous.


Hope this helps,
ibanix

$ echo '$0 & $0 &' > foo; chmod a+x foo; foo;