| .\" Copyright (c) 1993 Michael Haardt (michael@moria.de), |
| .\" Fri Apr 2 11:32:09 MET DST 1993 |
| .\" |
| .\" SPDX-License-Identifier: GPL-2.0-or-later |
| .\" |
| .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) |
| .\" Modified 2003-04-07 by Michael Kerrisk |
| .\" |
| .TH tty 4 (date) "Linux man-pages (unreleased)" |
| .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 with mode 0666 and ownership root:tty. |
| It is a synonym for the controlling terminal of a process, if any. |
| .P |
| 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. |
| .P |
| 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. |
| .P |
| 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 vcs (4), |
| .BR pty (7), |
| .BR agetty (8), |
| .BR mingetty (8) |
