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Manual Pages  — VIDCONTROL


vidcontrol – system console control and configuration utility



vidcontrol [-CdLHPpx] [-b color] [-c appearance] [ -f [ [size] file ] ] [-g geometry] [-h size] [-i active | 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) or vt(4) console driver, such as video mode, colors, cursor shape, screen output map, font and screen saver timeout. Only a small subset of options is supported by vt(4). Unsupported options lead to error messages, typically including the text "Inappropriate ioctl for device".

The following command line options are supported:
mode 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.
show 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 setting[,setting ...]
  Change the cursor appearance. The change is specified by a non-empty comma-separated list of settings. Each setting overrides or modifies previous ones in left to right order.

The following override settings are available:

  Set to a block covering 1 character cell, with a configuration-dependent coloring that should be at worst inverse video.
  Set to a blinking sub-block with height scanlines starting at base. The name "destructive" is bad for backwards compatibility. This setting should not force destructiveness, and it now only gives destructiveness in some configurations (typically for hardware cursors in text mode). Blinking limits destructiveness. This setting should now be spelled normal, blink, noblock. A non-blinking destructive cursor would be unusable, so old versions of vidcontrol didn't support it, and this version doesn't have an override for it.
base=value, height=value
  Set the specified scanline parameters. These parameters are only active in noblock mode. value is an integer in any base supported by strtol(3). Setting height to 0 turns off the cursor in noblock mode. Negative values are silently ignored. Positive values are clamped to fit in the character cell when the cursor is drawn.

The following modifier settings are available:
blink, noblink
  Set or clear the blinking attribute. This is not quite backwards compatible. In old versions of vidcontrol, was an override to a blinking block.
block, noblock
  Set or clear the block attribute. This attribute is the inverse of the flag CONS_CHAR_CURSOR in the implementation. It deactivates the scanline parameters, and expresses a preference for using a simpler method of implementation. Its inverse does the opposite. When the scanline parameters give a full block, this attribute reduces to a method selection bit. The block method tends to give better coloring.
hidden, nohidden
  Set or clear the hidden attribute.

The following (non-sticky) flags control application of the settings:
  Apply base and height to the (character) cursor's list of preferred colors instead of its shape. Beware that the color numbers are raw VGA palette indexes, not ANSI color numbers. The indexes are reduced mod 8, 16 or 256, or ignored, depending on the video mode and renderer.
  Colors for the mouse cursor in graphics mode. Like charcolors, except there is no preference or sequence; base gives the mouse border color and height gives the mouse interior color. Together with charcolors, this gives 2 selection bits which select between only 3 of 4 sub-destinations of the 4 destinations selected by default and local (by ignoring mousecolors if charcolors is also set).
  Apply the changes to the default settings and then to the active settings, instead of only to the active settings. Together with local, this gives 2 selection bits which select between 4 destinations.
  Ignore any changes to the block and hidden attributes.
local Apply the changes to the current vty. The default is to apply them to a global place and copy from there to all vtys.
reset Reset everything. The default is to not reset. When the local parameter is specified, the current local settings are reset to default local settings. Otherwise, the current global settings are reset to default global settings and then copied to the current and default settings for all vtys.
show Show the current changes.
  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.

When using vt(4) both size and font can be omitted, and the default font will be loaded.

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 either syscons(4) or vt(4) (depending on which driver you use).

-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 active
  Shows the active vty number.
-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) or vt(4) (depending on which driver you use).
  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 active 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.

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) or vt(4) (depending on which driver you use) for more details on this kernel option.

Format of Video Buffer Dump

The vidcontrol utility uses the syscons(4) or vt(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# Ta Ta width
meaning 7 Ta <X0000000> Ta 1 character blinking 6:4 Ta <0XXX0000> Ta 3 background color 3 Ta <0000X000> Ta 1 bright foreground color 2:0 Ta <00000XXX> Ta 3 foreground color

Here is a list of the three bit wide base colors:

0 Black
1 Blue
2 Green
3 Cyan
4 Red
5 Magenta
6 Brown
7 Light Grey

Base colors with bit 3 (the bright foreground flag) set:

0 Dark Grey
1 Light Blue
2 Light Green
3 Light Cyan
4 Light Red
5 Light Magenta
6 Yellow
7 White

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_"

File format version number

Remaining number of bytes in the header

Subsequent bytes depend on the version number.
Version Ta Byte Meaning

1 Ta 11
Terminal width, in characters

Ta 12
Terminal depth, in characters

Ta 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

Driver Configuration


  font files.
/usr/share/syscons/scrnmaps/* screen output map files (relevant for syscons(4) only).


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 (if using syscons) or /usr/share/vt/fonts (if using vt), 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), vt(4), rc.conf(5), kldload(8), moused(8), watch(8)

The various scr2* utilities in the graphics and textproc categories of the Ports Collection.


S/oren Schmidt <Mt sos@FreeBSD.org> Sascha Wildner <Mt saw@online.de>


Maxim Sobolev <Mt sobomax@FreeBSD.org>
Nik Clayton <Mt nik@FreeBSD.org>

VIDCONTROL (1) January 19, 2016

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