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.
chown(1), mknod(1), ioctl(2), ioctl_console(2),
ioctl_tty(2), termios(3), ttyS(4), vcs(4),
pty(7), agetty(8), mingetty(8)
This page is part of release 5.13 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the latest
version of this page, can be found at https://www.kernel.org/doc/man-pages/.