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VIDCONTROL(1) General Commands Manual VIDCONTROL(1)


vidcontrolsystem console control and configuration utility


vidcontrol [-CdLHPpx] [-b color] [-c appearance] [-f [size] file] [-g geometry] [-h size] [-i adapter | mode] [-l screen_map] [-M char] [-m on | off] [-r foreground background] [-S on | off] [-s number] [-T xterm | cons25] [-t N | off] [mode] [foreground [background]] [show]


The vidcontrol utility is used to set various options for the syscons(4) console driver, such as video mode, colors, cursor shape, screen output map, font and screen saver timeout.
The following command line options are supported:
Select a new video mode. The modes currently recognized are: 80x25, 80x30, 80x43, 80x50, 80x60, 132x25, 132x30, 132x43, 132x50, 132x60, VGA_40x25, VGA_80x25, VGA_80x30, VGA_80x50, VGA_80x60, VGA_90x25, VGA_90x30, VGA_90x43, VGA_90x50, VGA_90x60, EGA_80x25, EGA_80x43, VESA_132x25, VESA_132x43, VESA_132x50, VESA_132x60. The raster text mode VESA_800x600 can also be chosen. Alternatively, a mode can be specified with its number by using a mode name of the form MODE_NUMBER⟩. A list of valid mode numbers can be obtained with the -i mode option. See Video Mode Support below.
foreground [background]
Change colors when displaying text. Specify the foreground color (e.g. “vidcontrol white”), or both a foreground and background colors (e.g. “vidcontrol yellow blue”). Use the show command below to see available colors.
See the supported colors on a given platform.
-b color
Set border color to color. This option may not be always supported by the video driver.
Clear the history buffer.
-c normal | blink | destructive
Change the cursor appearance. The cursor is either an inverting block (normal) that can optionally blink, or it can be like the old hardware cursor (destructive). The latter is actually a simulation.
Print out current output screen map.
-f [size] file
Load font file for size (currently, only 8x8, 8x14 or 8x16). The font file can be either uuencoded or in raw binary format. You can also use the menu-driven vidfont(1) command to load the font of your choice.
Size may be omitted, in this case vidcontrol will try to guess it from the size of font file.
Note that older video cards, such as MDA and CGA, do not support software font. See also Video Mode Support and EXAMPLES below and the man page for syscons(4).
-g geometry
Set the geometry of the text mode for the modes with selectable geometry. Currently only raster modes, such as VESA_800x600, support this option. See also Video Mode Support and EXAMPLES below.
-h size
Set the size of the history (scrollback) buffer to size lines.
-i adapter
Shows info about the current video adapter.
-i mode
Shows the possible video modes with the current video hardware.
-l screen_map
Install screen output map file from screen_map. See also syscons(4).
Install default screen output map.
-M char
Sets the base character used to render the mouse pointer to char.
-m on | off
Switch the mouse pointer on or off. Used together with the moused(8) daemon for text mode cut & paste functionality.
Capture the current contents of the video buffer corresponding to the terminal device referred to by standard input. The vidcontrol utility writes contents of the video buffer to the standard output in a raw binary format. For details about that format see Format of Video Buffer Dump below.
Same as -p, but dump contents of the video buffer in a plain text format ignoring nonprintable characters and information about text attributes.
When used with -p or -P, it instructs vidcontrol to dump full history buffer instead of visible portion of the video buffer only.
-r foreground background
Change reverse mode colors to foreground and background.
-S on | off
Turn vty switching on or off. When vty switching is off, attempts to switch to a different virtual terminal will fail. (The default is to permit vty switching.) This protection can be easily bypassed when the kernel is compiled with the DDB option. However, you probably should not compile the kernel debugger on a box which is supposed to be physically secure.
-s number
Set the current vty to number.
-T xterm | cons25
Switch between xterm and cons25 style terminal emulation.
-t N | off
Set the screensaver timeout to N seconds, or turns it off.
Use hexadecimal digits for output.

Video Mode Support

Note that not all modes listed above may be supported by the video hardware. You can verify which mode is supported by the video hardware, using the -i mode option.
The VESA BIOS support must be linked to the kernel or loaded as a KLD module if you wish to use VESA video modes or 132 column modes (see vga(4)).
You need to compile your kernel with the VGA_WIDTH90 option if you wish to use VGA 90 column modes (see vga(4)).
Video modes other than 25 and 30 line modes may require specific size of font. Use -f option above to load a font file to the kernel. If the required size of font has not been loaded to the kernel, vidcontrol will fail if the user attempts to set a new video mode.
Modes Font size
25 line modes 8x16 (VGA), 8x14 (EGA)
30 line modes 8x16
43 line modes 8x8
50 line modes 8x8
60 line modes 8x8
It is better to always load all three sizes (8x8, 8x14 and 8x16) of the same font.
You may set variables in /etc/rc.conf or /etc/rc.conf.local so that desired font files will be automatically loaded when the system starts up. See below.
If you want to use any of the raster text modes you need to recompile your kernel with the SC_PIXEL_MODE option. See syscons(4) for more details on this kernel option.

Format of Video Buffer Dump

The vidcontrol utility uses the syscons(4) CONS_SCRSHOT ioctl(2) to capture the current contents of the video buffer. The vidcontrol utility writes version and additional information to the standard output, followed by the contents of the video buffer.
VGA video memory is typically arranged in two byte tuples, one per character position. In each tuple, the first byte will be the character code, and the second byte is the character's color attribute.
The VGA color attribute byte looks like this:
bits# width meaning
7 <X0000000> 1 character blinking
6:4 <0XXX0000> 3 background color
3 <0000X000> 1 bright foreground color
2:0 <00000XXX> 3 foreground color
Here is a list of the three bit wide base colors:
Light Grey
Base colors with bit 3 (the bright foreground flag) set:
Dark Grey
Light Blue
Light Green
Light Cyan
Light Red
Light Magenta
For example, the two bytes
65 158
specify an uppercase A (character code 65), blinking (bit 7 set) in yellow (bits 3:0) on a blue background (bits 6:4).
The vidcontrol output contains a small header which includes additional information which may be useful to utilities processing the output.
The first 10 bytes are always arranged as follows:
Byte Range Contents
1 thru 8 Literal text “SCRSHOT_
9 File format version number
10 Remaining number of bytes in the header
Subsequent bytes depend on the version number.
Sy Version Byte Meaning
1 11 Terminal width, in characters
12 Terminal depth, in characters
13 and up The snapshot data
So a dump of an 80x25 screen would start (in hex)
53 43 52 53 48 4f 54 5f 01 02 50 19 
----------------------- -- -- -- -- 
          |              |  |  |  ` 25 decimal 
          |              |  |  `--- 80 decimal 
          |              |  `------ 2 remaining bytes of header data 
          |              `--------- File format version 1 
          `------------------------ Literal "SCRSHOT_"


Boot Time Configuration

You may set the following variables in /etc/rc.conf or /etc/rc.conf.local in order to configure the video output at boot time.
Sets the timeout value for the -t option.
font8x16, font8x14, font8x8
Specifies font files for the -f option.
Specifies a screen output map file for the -l option.
See rc.conf(5) for more details.

Driver Configuration

The video card driver may let you change default configuration options, such as the default font, so that you do not need to set up the options at boot time. See video card driver manuals, (e.g. vga(4)) for details.


font files.
screen output map files.


If you want to load /usr/share/syscons/fonts/iso-8x16.fnt to the kernel, run vidcontrol as:
vidcontrol -f 8x16 /usr/share/syscons/fonts/iso-8x16.fnt
So long as the font file is in /usr/share/syscons/fonts, you may abbreviate the file name as iso-8x16:
vidcontrol -f 8x16 iso-8x16
Furthermore, you can also omit font size “8x16”:
vidcontrol -f iso-8x16
Moreover, the suffix specifying the font size can be also omitted; in this case, vidcontrol will use the size of the currently displayed font to construct the suffix:
vidcontrol -f iso
Likewise, you can also abbreviate the screen output map file name for the -l option if the file is found in /usr/share/syscons/scrnmaps.
vidcontrol -l iso-8859-1_to_cp437
The above command will load /usr/share/syscons/scrnmaps/iso-8859-1_to_cp437.scm.
The following command will set-up a 100x37 raster text mode (useful for some LCD models):
vidcontrol -g 100x37 VESA_800x600
The following command will capture the contents of the first virtual terminal video buffer, and redirect the output to the shot.scr file:
vidcontrol -p < /dev/ttyv0 > shot.scr
The following command will dump contents of the fourth virtual terminal video buffer to the standard output in the human readable format:
vidcontrol -P < /dev/ttyv3


kbdcontrol(1), vidfont(1), keyboard(4), screen(4), syscons(4), vga(4), rc.conf(5), kldload(8), moused(8), watch(8)
The various scr2* utilities in the graphics and textproc categories of the Ports Collection.


Søren Schmidt ⟨⟩
Sascha Wildner


Maxim Sobolev ⟨⟩,
Nik Clayton ⟨⟩
December 23, 2006 Debian