NAME
console - console terminal and virtual consoles
DESCRIPTION
A Linux system has up to 63 virtual consoles (character dev-
ices 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 getty(8) on the console;
(b) ask open(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 con-
soles; (c) use the program chvt(1). (The key mapping is
user settable, see loadkeys(1); the above mentioned key com-
binations 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 associated 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 terminals. 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
charsets(4), console_codes(4), console_ioctl(4), mknod(1),
tty(4), ttys(4), getty(8), init(8), chvt(1), open(1), deal-
locvt(1), loadkeys(1), resizecons(8), setfont(8), mapscrn(8)