TTY(4)                     Linux Programmer's Manual                    TTY(4)

NAME

       tty - controlling terminal

DESCRIPTION

       The  file  /dev/tty  is  a character file with major number 5 and minor
       number 0, usually of mode 0666 and owner.group root.tty.  It is a  syn-
       onym for the controlling terminal of a process, if any.

       In  addition  to  the ioctl() requests supported by the device that tty
       refers to, the ioctl() request TIOCNOTTY is supported.

   TIOCNOTTY
       Detach the current process from its controlling terminal.

       If the process is the session leader, then SIGHUP and  SIGCONT  signals
       are  sent to the foreground process group and all processes in the cur-
       rent session lose their controlling tty.

       This ioctl() call only works on file descriptors connected to /dev/tty.
       It  is  used  by  daemon processes when they are invoked by a user at a
       terminal.  The process attempts to open /dev/tty. If the open succeeds,
       it  detaches  itself from the terminal by using TIOCNOTTY, while if the
       open fails, it is obviously not attached to a  terminal  and  does  not
       need to detach itself.

FILES

       /dev/tty

SEE ALSO

       chown(1), getty(1), mknod(1), ioctl(2), termios(3), console(4), ttyS(4)

Linux                             2003-04-07                            TTY(4)