Generally, don't write code that attempts to "background itself". Leave that to whatever "service manager" is used by the system - init à la BSD, init scripts, daemontools, runit, whatever. Just let the program run in foreground.

I prefer daemontools (running on Slackware, not Debian). See this search for details.

Note that there are Debian packages for daemontools and runit, so you can use either service manager on Debian and simply let your package depend on one of those packages.

Alexander