kurahaupo_mobile 1390561568 learn every process has a PID, a process group (PGRP, which is its own PID, or the PGRP inherited ftom its parent), and a session (SID). All processses in a PGRP have the same SID. A terminal has a session & a foreground process group (which must be in the same SID). If the terminal's SID changes, all the processes with that SID get SIGHUP. If you type ctrl-C or ctrl-Z then the PGRP gets SIGINT or SIGTSTP