The easiest way to make a script run in the background is just by putting an & after the command (if you are using a standard unix shell). If you want to make a program that backgrounds on its own, you should fork and then use the "setsid" command.

use POSIX qw(setsid);
exit if fork();  # parent dies
setsid;  # make this a new process group
... rest of your program ...
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