FbTerm - a fast Frame Buffer based TERMinal emulator for linux
fbterm [options] [--] [command [arguments]]
FbTerm is a fast terminal emulator for linux with frame buffer device
or VESA video card. Features include:
* mostly as fast as terminal of linux kernel while accelerated
scrolling is enabled
* select font with fontconfig and draw text with freetype2, same as
Qt/Gtk+ based GUI apps
* dynamically create/destroy up to 10 windows initially running
* record scroll-back history for every window
* auto-detect current locale and convert text encoding, support
double width scripts like Chinese, Japanese etc
* switch between configurable additional text encodings with hot keys
on the fly
* copy/past selected text between windows with mouse when gpm server
* change the orientation of screen display, a.k.a. screen rotation
* lightweight input method framework with client-server architecture
* background image for eye candy
command [arguments] may be given to override the built-in choice of
shell program. Normally FbTerm checks the SHELL variable. If that is
not set, it tries to use the user's login shell program specified in
the password file. If that is not set, /bin/sh will be used. You should
use the -- argument to separate FbTerm's options from the arguments
supplied to the command.
FbTerm first uses option value specified in command line arguments,
then in the configure file $HOME/.fbtermrc. If that file doesn't
exist, FbTerm will create it with default options on startup.
display the help and exit
display FbTerm version and exit
display extra FbTerm's information
specify font family names
specify font pixel size
force font width
force font height
specify foreground color
specify background color
specify additional text encodings
treat ambiguous width characters as wide
specify the orientation of screen display
specify input method program
specify default cursor shape
specify cursor flash interval
specify VESA video mode
display available VESA video modes
see comments in $HOME/.fbtermrc for details of these options.
CTRL_ALT_E: exit from FbTerm
CTRL_ALT_C: create a new window
CTRL_ALT_D: destroy current window
CTRL_ALT_1: switch to window 1
CTRL_ALT_2: switch to window 2
CTRL_ALT_3: switch to window 3
CTRL_ALT_4: switch to window 4
CTRL_ALT_5: switch to window 5
CTRL_ALT_6: switch to window 6
CTRL_ALT_7: switch to window 7
CTRL_ALT_8: switch to window 8
CTRL_ALT_9: switch to window 9
CTRL_ALT_0: switch to window 10
SHIFT_LEFT: switch to previous window
SHIFT_RIGHT: switch to next window
SHIFT_PAGEUP: history scroll up
SHIFT_PAGEDOWN: history scroll down
CTRL_ALT_F1: switch to encoding of current locale
CTRL_ALT_F2 to CTRL_ALT_F6: switch to additional encodings
CTRL_SPACE: toggle input method
CTRL_ALT_K: kill input method server
move when left button down: select text
double click with left button: auto select text
click with right button: paste selected text
Sometimes above actions will not work, please try to redo them with
shift key holding down.
FRAME BUFFER DEVICE
Before executing FbTerm, make sure there is a frame buffer device in
your system, and you have read/write access right with it. Normally
FbTerm tries to open /dev/fb0 and /dev/fb/0, environment variable
"FRAMEBUFFER" may be used to override this built-in behavior.
VESA VIDEO DEVICE
From version 1.6, FbTerm adds VESA video card support. By default,
FbTerm tries frame buffer device first, if failure, then tries to use
VESA device with highest resolution and color depth. option "vesa-mode"
may be given to force only open VESA device with the specified video
mode. To see available video modes for your VESA card, execute "fbterm
Attention: 1) VESA support requires root privilege to work; 2) do not
force to use VESA device on the system with frame buffer device
enabled, they maybe conflict with each other.
FbTerm invokes fontconfig to get a font list, if the first font doesn't
contain the glyph for the rendering character, it will try second font,
then the third, ... and so on, user can see this ordered font list with
If you don't like the fonts selected by FbTerm, execute "fc-list" to
get available fonts, choose favorites as the value of option "font-
names". You may also modify the configure file of fontconfig, which
will change the behavior of all programs based on fontconfig!
By using iconv, FbTerm converts other encodings to internal encoding
UTF-8. On startup, FbTerm checks variable LC_CTYPE to determine the
default text encoding, which is binded to shortcut CTRL_ALT_F1. User
can specify up to 5 additional encodings with option "text-encodings",
for example, as a Chinese user, you set "text-encodings=gbk,big5",
shortcut CTRL_ALT_F2 will bind to gbk, and CTRL_ALT_F3 bind to big5.
In a number of CJK encodings there are ambiguous width characters which
have a width of either narrow or wide depending on the context of their
use. By default, FbTerm treats them as narrow width characters, option
"ambiguous-wide" may be used to change the behavior.
FbTerm doesn't load and parse any image file with various formats
directly, instead it takes a screen shot of frame buffer device on
startup if variable FBTERM_BACKGROUND_IMAGE is defined, then uses this
screen shot as the background for text rendering. In order to enable
background image support, user should first put a image to frame buffer
device with a image viewer. A wrapper script using fbv is listed below:
# fbterm-bi: a wrapper script to enable background image with
# usage: fbterm-bi /path/to/image fbterm-options
echo -ne "[?25l" # hide cursor
fbv -ciuker "$1" << EOF
exec fbterm "$@"
Attention: 1) do not enable background image on frame buffer device
with 8bpp depth, because FbTerm changes color map table for correct
text rendering; 2) if the screen shot is different from the original
image, try to use a fast scrolling disabled frame buffer device.
256 COLOR EXTENSION
FbTerm supports xterm's 256 color mode extension. The first 16 colors
are the default terminal colors. Additionally, there's a 6x6x6 color
cube, and 24 grayscale tones. But xterm's 256 color escape sequences
conflict with the linux sequences implemented by FbTerm, so private
escape sequences were introduced to support this feature:
ESC [ 1 ; n } set foreground color to n (0 - 255)
ESC [ 2 ; n } set background color to n (0 - 255)
ESC [ 3 ; n ; r ; g ; b } set color n to (r, g, b) , n, r,
g, b all in (0 - 255)
A new terminfo database entry named "fbterm" was added to use these
private sequences, all program based on terminfo should work with it.
By default, FbTerm sets environment variable "TERM" to value "linux",
user need run "TERM=fbterm /path/to/program" to enable 256 color mode.
Instead of adding input method directly in FbTerm, a client-server
based input method framework is designed to do this work. FbTerm acts
as a client, standalone IM program as a server, and they run in
As a normal IM user, you should install a IM program written for
FbTerm, and specify it as the value of option "input-method".
CTRL_SPACE is the shortcut to activate/deactivate input method. And
CTRL_ALT_K may be used to kill the IM program when it has freezed.
FbTerm tries to change linux kernel key map table to setup shortcuts,
which requires SYS_TTY_CONFIG capability since kernel version 2.6.15.
It means FbTerm should be a setuid 0 program to allow non-root users to
use shortcuts. FbTerm only switches to root privilege temporarily when
changing key map table, we believe it's pretty much free from security
problems. If you really don't like this and have a linux kernel with
file system capabilities enabled, which allow user to give binaries a
subset of root's powers without using setuid 0 (official kernel 2.6.27
includes it), you can run command "sudo setcap 'cap_sys_tty_config+ep'
FbTerm redirects /dev/tty0 output to the pseudo terminal of current
sub-window. In linux before version 2.6.10, anybody can do this as long
as the output was not redirected yet; since version 2.6.10, only root
or a process with the CAP_SYS_ADMIN capability may do this. You should
do similar work with above ones for FbTerm to enable this feature for
According test result, FbTerm spends more than 95% time on painting
screen. Speedup painting will significantly increase performance. Here
are some suggestions for frame buffer device:
* Enable fast scrolling on frame buffer device. The visible screen
will be just a window of the video memory, when scrolling, FbTerm only
change the start of window, no need to repaint the whole screen.
* On Intel P6 family processors the Memory Type Range Registers
(MTRRs) may be used to control processor access to memory ranges. If
you have video card on a PCI or AGP bus, enabling write-combining
allows bus write transfers to be combined into a larger transfer before
bursting over the PCI/AGP bus. This can increase performance of
FbTerm's paint operations.
Maybe you need to enable them manually for your video card. For
example, by default fast scrolling and write-combining are all disabled
on general VESA frame buffer device, GRUB/LILO configure file should be
modified to enable them. A GRUB example is showed below:
kernel /boot/vmlinuz ro root=LABEL=UBUNTU splash vga=0x317
You may check fast scrolling status with "fbterm -v", a message with
"scrolling: redraw" means fast scrolling is disabled, otherwise
Written by dragchan.
Please submit bug reports to <http://code.google.com/p/fbterm/issues>.
Copyright © 2008-2010 dragchan. License GPLv2: GNU GPL version 2 or
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.