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 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.
TIOCNOTTY
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 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.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
