.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),

.\"     Fri Apr  2 11:32:09 MET DST 1993

.\"

.\" %%%LICENSE_START(GPLv2+_DOC_FULL)

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.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)

.\" Modified 2003-04-07 by Michael Kerrisk

.\"

.TH TTY 4 2017-11-26 "Linux" "Linux Programmer's Manual"

.SH NAME

tty \- controlling terminal

.SH DESCRIPTION

The file

.I /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.

.PP

In addition to the

.BR ioctl (2)

requests supported by the device that

.B tty

refers to, the

.BR ioctl (2)

request

.B TIOCNOTTY

is supported.

.SS TIOCNOTTY

Detach the calling process from its controlling terminal.

.PP

If the process is the session leader,

then

.B SIGHUP

and

.B SIGCONT

signals are sent to the foreground process group

and all processes in the current session lose their controlling tty.

.PP

This

.BR ioctl (2)

call works only on file descriptors connected

to

.IR /dev/tty .

It is used by daemon processes when they are invoked

by a user at a terminal.

The process attempts to open

.IR /dev/tty .

If the open succeeds, it

detaches itself from the terminal by using

.BR TIOCNOTTY ,

while if the

open fails, it is obviously not attached to a terminal and does not need

to detach itself.

.SH FILES

.I /dev/tty

.SH SEE ALSO

.BR chown (1),

.BR mknod (1),

.BR ioctl (2),

.BR ioctl_console (2),

.BR ioctl_tty (2),

.BR termios (3),

.BR ttyS (4),

.BR agetty (8),

.BR mingetty (8)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I 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/.