ok, understood. i'll check all supported code for not full correct check of do() execution :

And now issue transforms to:
- create file 'test.pl' with content:

print "err = '$!'\n";
exit 0;
[download]

without \n in the end

- run file by command like:
`perl ./test.pl`

- see in output:

$ perl ./test3.pl
err = 'Bad file descriptor'

and question now is "why perl sets $! for file w/o \n in the end"...

Thanks,
alex|sawoy|slex