FbTerm(1) FbTerm User Manual FbTerm(1)
NAME
FbTerm - a fast Frame Buffer based TERMinal emulator for linux
SYNOPSIS
fbterm [options] [--] [command [arguments]]
DESCRIPTION
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 de-
fault shell
* 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
is running
* change the orientation of screen display, a.k.a. screen rotation
* lightweight input method framework with client-server architecture
* background image for eye candy
OPTIONS
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.
-h, --help
display the help and exit
-V, --version
display FbTerm version and exit
-v, --verbose
display extra FbTerm's information
-n, --font-names=text
specify font family names
-s, --font-size=num
specify font pixel size
--font-width=num
force font width
--font-height=num
force font height
-f, --color-foreground=num
specify foreground color
-b, --color-background=num
specify background color
-e, --text-encodings=text
specify additional text encodings
-a, --ambiguous-wide
treat ambiguous width characters as wide
-r, --screen-rotate=num
specify the orientation of screen display
-i, --input-method=text
specify input method program
--cursor-shape=num
specify default cursor shape
--cursor-interval=num
specify cursor flash interval
--vesa-mode=num
specify VESA video mode
--vesa-mode=list
display available VESA video modes
see comments in $HOME/.fbtermrc for details of these options.
SHORTCUT SUMMARY
keyboard:
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
mouse:
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
--vesa-mode=list".
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.
FONT
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
"fbterm -v".
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!
TEXT ENCODING
By using iconv, FbTerm converts other encodings to internal encoding
UTF-8. On startup, FbTerm checks variable LC_CTYPE to determine the de-
fault 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.
BACKGROUND IMAGE
FbTerm doesn't load and parse any image file with various formats di-
rectly, 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:
#!/bin/bash
# fbterm-bi: a wrapper script to enable background image with fbterm
# usage: fbterm-bi /path/to/image fbterm-options
echo -ne "\e[?25l" # hide cursor
fbv -ciuker "$1" << EOF
q
EOF
shift
export FBTERM_BACKGROUND_IMAGE=1
exec fbterm "$@"
Attention: 1) do not enable background image on frame buffer device with
8bpp depth, because FbTerm changes color map table for correct text ren-
dering; 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 es-
cape 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 pri-
vate 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.
INPUT METHOD
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 separated
processes.
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.
SECURITY NOTES
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'
/path/to/fbterm".
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 non-
root users.
PERFORMANCE
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 gen-
eral VESA frame buffer device, GRUB/LILO configure file should be modi-
fied to enable them. A GRUB example is showed below:
title Ubuntu
root (hd0,0)
kernel /boot/vmlinuz ro root=LABEL=UBUNTU splash vga=0x317
video=vesafb:ywrap,mtrr:3
initrd /boot/initrd.img
You may check fast scrolling status with "fbterm -v", a message with
"scrolling: redraw" means fast scrolling is disabled, otherwise enabled.
AUTHOR
Written by dragchan.
REPORTING BUGS
Please submit bug reports to <http://code.google.com/p/fbterm/issues>.
COPYRIGHT
Copyright © 2008-2010 dragchan. License GPLv2: GNU GPL version 2 or
later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
FbTerm 1.7 October 2010 FbTerm(1)
Generated by dwww version 1.16 on Sat Oct 3 06:46:38 CEST 2026.