|VIDCONTROL(1)||General Commands Manual||VIDCONTROL(1)|
system console control and configuration utility
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
The following command line options are supported:
- Select a new video mode. The modes currently recognized are:
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
modeoption. 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
showcommand below to see available colors.
- See the supported colors on a given platform.
- Set border color to color. This option may not be always supported by the video driver.
- Clear the history buffer.
- 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.
- Load font file for size
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
vidcontrolwill 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).
- 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.
- Set the size of the history (scrollback) buffer to size lines.
- Shows info about the current video adapter.
- Shows the possible video modes with the current video hardware.
- 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.
- Sets the base character used to render the mouse pointer to char.
- Switch the mouse pointer
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
vidcontrolutility 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, it instructs
vidcontrolto dump full history buffer instead of visible portion of the video buffer only.
- Change reverse mode colors to foreground and background.
- 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
DDBoption. However, you probably should not compile the kernel debugger on a box which is supposed to be physically secure.
- Set the current vty to number.
- Switch between xterm and cons25 style terminal emulation.
- Set the screensaver timeout to N seconds, or turns
- 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,
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
vidcontrol will fail if the user attempts to
set a new video mode.
|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
See syscons(4) or vt(4) (depending on
which driver you use) for more details on this kernel option.
Format of Video Buffer Dump¶
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
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:
||<0000X000>||1||bright 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
specify an uppercase A (character code 65), blinking (bit 7 set) in yellow (bits 3:0) on a blue background (bits 6:4).
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:
|1 thru 8||Literal text “
|9||File format version number|
|10||Remaining number of bytes in the header|
Subsequent bytes depend on the version number.
|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_"
VIDEO OUTPUT CONFIGURATION¶
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
- font8x16, font8x14, font8x8
- Specifies font files for the
- Specifies a screen output map file for the
See rc.conf(5) for more details.
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 (relevant for syscons(4) only).
If you want to load
/usr/share/syscons/fonts/iso-8x16.fnt to the kernel,
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
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
-l option if the file is found in
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
The various scr2* utilities in the graphics and textproc categories of the Ports Collection.
Nik Clayton ⟨nik@FreeBSD.org⟩
|December 23, 2006||Debian|