console - console terminal and virtual consoles


     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

     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.


     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).




     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)