tty - controlling terminal
The file
/dev/tty is a character file with major number 5 and minor
number 0, usually with mode 0666 and ownership root:tty. It is a synonym for
the controlling terminal of a process, if any.
In addition to the
ioctl(2) requests supported by the device that
tty refers to, the
ioctl(2) request
TIOCNOTTY is
supported.
Detach the calling 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
current session lose their controlling tty.
This
ioctl(2) call works only 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.
/dev/tty
chown(1),
mknod(1),
ioctl(2),
ioctl_console(2),
ioctl_tty(2),
termios(3),
ttyS(4),
vcs(4),
pty(7),
agetty(8),
mingetty(8)