4:console
From Linux Man Pages
console - console terminal and virtual consoles
Contents |
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 cre-
ated 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 getty(8) on the con-
sole; (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+RightAr-
row 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 set-
tings.)
The command deallocvt(1) (formerly disalloc) will free the memory taken by the screen buffers for consoles that
no longer have any associated process.
PROPERTIES
Consoles carry a lot of state. I hope to document that some other time. The most important fact is that the con-
soles simulate vt100 terminals. In particular, a console is reset to the initial state by printing the two char-
acters ESC c. All escape sequences can be found in console_codes(4).
FILES
/dev/console
/dev/tty*
RELATED
chvt(1), deallocvt(1), loadkeys(1), mknod(1), openvt(1), console_codes(4), console_ioctl(4), tty(4), ttyS(4), charsets(7), getty(8), init(8), mapscrn(8), resizecons(8), setfont(8)