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This page displays the COHERENT manpage for virtual console [COHERENT system of multiple virtual consoles].
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virtual console -- Technical Information COHERENT system of multiple virtual consoles The ``virtual consoles'' feature of COHERENT allows you to run multiple sessions from the system console. You can switch between sessions on the console screen using the appropriate keystrokes. If your computer has both monochrome and color video adapters and monitors, you can run multiple sessions on both screens simultaneously. For this feature to be available, your system must be configured for virtual consoles. Normally, this configuration is done during installation. In addition, virtual console sessions must be enabled for logins prior to use. Virtual terminals are most useful when your system is running in multiuser mode. COHERENT allows up to ten sessions at a given time. All you need to do to access multiple sessions is to hold down the <Ctrl> key on the system keyboard and press the digit on the numeric keypad corresponding to the desired active session number. Simultaneously pressing keys <Ctrl> and <.> (located on the numeric keypad) will take you to the next open virtual terminal session. Another means of switching sessions is to hold down the <Alt> key and press one of the ``function keys''. By default, function key <F10> takes you to the next open virtual terminal session, <F11> takes you to the previous open virtual terminal session, and <F12> toggles between the current and previously selected sessions. Technical Features It is not essential to know the following in order to use virtual terminals. We provide this information for advanced users, as well as persons wishing to customize their systems in ways not available under the default scheme used by the COHERENT installation procedure. Different sessions are accessed by using different device names in directory /dev. Like any character special device, each virtual terminal screen has a major and minor number associated with it. The major number for all virtual terminal screens is 2. The device with minor number 0 is initially the console device -- this is where output appears during startup and at other times when the system is in single-user mode. Virtual terminals are assigned successive minor numbers. When there are both color and monochrome display adapters on the system, the color sessions are given the lower minor numbers. For example, in a system configured for four color and four monochrome sessions, logical devices might be numbered as follows: crwxr-xr-x 1 root root 2 0 Mon Jun 15 14:51 /dev/console crwxr-xr-x 1 root root 2 1 Mon Jun 15 14:51 /dev/vcolor0 crwxr-xr-x 1 root root 2 2 Mon Jun 15 14:51 /dev/vcolor1 crwxr-xr-x 1 root root 2 3 Mon Jun 15 14:51 /dev/vcolor2 crwxr-xr-x 1 root root 2 4 Mon Jun 15 14:51 /dev/vcolor3 crwxr-xr-x 1 root root 2 5 Mon Jun 15 14:50 /dev/vmono0 crwxr-xr-x 1 root root 2 6 Mon Jun 15 14:50 /dev/vmono1 crwxr-xr-x 1 root root 2 7 Mon Jun 15 14:50 /dev/vmono2 crwxr-xr-x 1 root root 2 8 Mon Jun 15 14:50 /dev/vmono3 Alternatively, using physical device numbering, successive color-only sessions can be accessed by using minor numbers 64-79, while successive monochrome-only sessions are selected with minor numbers 80-95. The configuration of four color plus four monochrome sessions described above could also be represented as: crwxr-xr-x 1 root root 2 64 Mon Jun 15 14:51 /dev/color0 crwxr-xr-x 1 root root 2 65 Mon Jun 15 14:51 /dev/color1 crwxr-xr-x 1 root root 2 66 Mon Jun 15 14:51 /dev/color2 crwxr-xr-x 1 root root 2 67 Mon Jun 15 14:51 /dev/color3 crwxr-xr-x 1 root root 2 80 Mon Jun 15 14:50 /dev/mono0 crwxr-xr-x 1 root root 2 81 Mon Jun 15 14:50 /dev/mono1 crwxr-xr-x 1 root root 2 82 Mon Jun 15 14:50 /dev/mono2 crwxr-xr-x 1 root root 2 83 Mon Jun 15 14:50 /dev/mono3 The following diagram summarizes bit assignments in the virtual terminal minor number: 7654 3210 | 1=physical device, 0=logical device || 00=color, 01=mono, 1x=reserved |||| terminal's index number The system initially defaults to a maximum of four color and four monochrome sessions. This may be altered by patching character variables VTVGA and VTMONO. For example, to allow for six color and three monochrome sessions, enter the following command while running as root (note that this will not take effect until after the system has been rebooted): /conf/patch -v /coherent VTVGA=6:c VTMONO=3:c Running multiple sessions on different virtual consoles requires that logins be enabled for each of the virtual consoles. Each session must have a corresponding entry in file /etc/ttys. For example, a system allowing four color and four monochrome sessions would have entries in /etc/ttys as follows: 0lPconsole 1lPcolor0 1lPcolor1 1lPcolor2 1lPcolor3 1lPmono0 1lPmono1 1lPmono2 1lPmono3 Device /dev/console must not be enabled when using virtual consoles! Additional lines would be present if logins are enabled for other devices such as serial ports. Commands enable and disable may be used, as usual, to allow or disallow logins on individual virtual consoles. When virtual terminals are enabled, kernel output, such as messages about user traps or system panics, goes to the currently active session (i.e., the session with the cursor showing). Altering Virtual Consoles To add, delete, or alter the configuration of virtual consoles, log in as the superuser root and type the following commands: cd /etc/conf console/mkdev bin/idmkcoh -o /kernel_name where kernel_name is what you wish to name the newly built kernel. When you reboot, invoke kernel_name in the usual manner and your new configuration will have been implemented. See Also Administering COHERENT, console, device drivers, enable, kb.h Notes Some confusion can arise when you attempt to install COHERENT to use both color and monochrome consoles. At installation time, you are asked if you want to install both color and monochrome screens. If you reply ``yes,'' you must select only four multiscreens for each. Otherwise, you will find it difficult to address virtual consoles on both consoles: COHERENT uses the lower function keys for virtual consoles on the color monitor, and the upper function keys for those on the monochrome monitor. If you have requested two consoles, COHERENT uses the color terminal by default. If you really have only a monochrome monitor plugged into your system, you must invoke the appropriate monochrome virtual console; otherwise, you will nothing on your monitor.