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tty(4) [linux man page]

TTY(4)							     Linux Programmer's Manual							    TTY(4)

tty - controlling terminal DESCRIPTION
The file /dev/tty is a character file with major number 5 and minor number 0, usually of mode 0666 and root.tty. It is a syn- onym 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. FILES
/dev/tty SEE ALSO
chown(1), mknod(1), ioctl(2), termios(3), console(4), tty_ioctl(4), ttyS(4), agetty(8), mingetty(8) COLOPHON
This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at Linux 2003-04-07 TTY(4)

Check Out this Related Man Page

CONSOLE(4)						     Linux Programmer's Manual							CONSOLE(4)

console - console terminal and virtual consoles DESCRIPTION
A Linux system has up to 63 virtual consoles (character devices with major number 4 and minor number 1 to 63), usually called /dev/ttyn with 1 <= n <= 63. The current console is also addressed by /dev/console or /dev/tty0, the character device with major number 4 and minor number 0. The device files /dev/* are usually created using the script MAKEDEV, or using mknod(1), usually with mode 0622 and owner root.tty. Before kernel version 1.1.54 the number of virtual consoles was compiled into the kernel (in tty.h: #define NR_CONSOLES 8) and could be changed by editing and recompiling. Since version 1.1.54 virtual consoles are created on the fly, as soon as they are needed. Common ways to start a process on a console are: (a) tell init(8) (in inittab(5)) to start a mingetty(8) (or agetty(8)) on the console; (b) ask openvt(1) to start a process on the console; (c) start X--it will find the first unused console, and display its output there. (There is also the ancient doshell(8).) Common ways to switch consoles are: (a) use Alt+Fn or Ctrl+Alt+Fn to switch to console n; AltGr+Fn might bring you to console n+12 [here Alt and AltGr refer to the left and right Alt keys, respectively]; (b) use Alt+RightArrow or Alt+LeftArrow to cycle through the presently allocated consoles; (c) use the program chvt(1). (The key mapping is user settable, see loadkeys(1); the above mentioned key combinations are according to the default settings.) The command deallocvt(1) (formerly disalloc) will free the memory taken by the screen buffers for consoles that no longer have any associ- ated process. Properties Consoles carry a lot of state. I hope to document that some other time. The most important fact is that the consoles simulate vt100 ter- minals. In particular, a console is reset to the initial state by printing the two characters ESC c. All escape sequences can be found in console_codes(4). FILES
/dev/console /dev/tty* SEE ALSO
chvt(1), deallocvt(1), loadkeys(1), mknod(1), openvt(1), console_codes(4), console_ioctl(4), tty(4), ttyS(4), charsets(7), agetty(8), init(8), mapscrn(8), mingetty(8), resizecons(8), setfont(8) COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at Linux 1994-10-31 CONSOLE(4)

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