Took me a while to understand and check. Indeed, omitting the second argument entirely seems to be the correct patch.

I'm not fully sure yet how the output is used; BackupPC's source is not necessarily easy to read/follow and I'm not at all 'fluent' in it. But as the changes to config values (done via CGI) are merged with the values read in from the old config files, as strings into executable config.pl files, there sure is some later eval() somewhere.

Thank you!