Modem disconnect

The following arrangements are made to allow processes that read from a terminal-device-file and test for end-of-file to terminate appropriately when a modem-disconnect is detected on the terminal-device:

• All processes with that terminal as the controlling terminal receive a hang-up signal, SIGHUP, if CLOCAL is clear in the c_cflags for the terminal (see ``Control modes'' and termios(3C)). Unless other arrangements are made, the signal SIGHUP forces the processes to terminate (see signal(5) and sigaction(2)). If the signal SIGHUP is ignored or caught by a signal-catching function, any subsequent read returns 0 to indicate end-of-file until the terminal-device-file is closed (see read(2)).

• If the controlling process is not in the foreground process group of the terminal, the signal SIGTSTP is sent to all processes in the foreground process group for which the terminal is the controlling terminal. Unless other arrangements are made, the signal SIGTSTP forces the processes to terminate (see signal(5) and sigaction(2)).

• Processes in background process groups that try a read or a write of the controlling terminal after a modem-disconnect while the terminal is still assigned to the session receive the appropriate signal, SIGTTIN or SIGTTOU respectively (see read(2) and write(2)). Unless other arrangements are made, the signal SIGTTIN or SIGTTOU forces the processes to terminate (see signal(5) and sigaction(2)).