<code> use threads; use threads::shared; $SIG{'HUP'}='switchFlag'; $flag::shared; my $thr=threads->new(\&printer); $thr->detach(); sleep 10000; print "I am here\n"; exit; sub printer{ while(1) { sleep 1; print "Shared: $flag\n"; } } sub switchFlag{ $flag=!$flag; print "signal caught"; $SIG{'HUP'}='switchFlag'; }