consolefs(4) [plan9 man page]
CONSOLEFS(4) Kernel Interfaces Manual CONSOLEFS(4) NAME
consolefs, C - file system for console access SYNOPSIS
aux/consolefs name dev [ name dev ... ] C system DESCRIPTION
To ease administration of multiple machines one might attach many serial console lines to a single computer. Consolefs is a file system that lets multiple users simultaneously access these console lines. Each name/dev pair represents the name of a console and the serial line device associated with it. Consolefs presents a single level directory with two files per console: name and namectl. Writes of name are equivalent to writes of dev and reads and writes of namectl are equivalent to reads and writes of devctl. Consolefs broadcasts any- thing it reads from dev to all readers of name. Therefore, many users can con(1) to a name, see all console output, and enter commands to the console. To keep users from inadvertently interfering with one another, notification is broadcast to all readers whenever a user opens or closes name. For example, if user boris opens a console that users vlad and barney have already opened, all will read the message: [+boris, vlad, barney] If vlad then closes, boris and barney will read: [-vlad, boris, barney] Consolefs posts the client end of its 9P channel in /srv/consolefs; mount (see bind(1)) this file to see the consoles. An example of 2 consoles complete with console logging is: % aux/consolefs bootes /dev/eia0 fornax /dev/eia1 % mount /srv/consoles /mnt/consoles % ls -p /mnt/consoles bootes bootesctl fornax fornaxctl % cat /mnt/consoles/fornax >> /sys/log/fornax & % cat /mnt/consoles/bootes >> /sys/log/bootes & The rc(1) script C automates this procedure. It uses import(4) to connect to /mnt/consoles on the machine connected to all the consoles, then uses con(1) to connect to the console of the machine system. The script must be edited at installation by the local administration to identify the system that holds /mnt/consoles. FILES
/srv/consoles Client end of pipe to server. SOURCE
/sys/src/cmd/aux/consolefs.l /rc/bin/C CONSOLEFS(4)
Check Out this Related Man Page
CONSOLE(4) Linux User's Manual CONSOLE(4) NAME
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 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 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 termi- nals. 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), deallocvt(1), loadkeys(1), resizecons(8), consolechars(8), mapscrn(8). Console tools 28 Oct 1997 CONSOLE(4)