BRLTTY(1) The BRLTTY Project BRLTTY(1)NAMEbrltty - refreshable braille display driver for Linux/Unix
SYNOPSISbrltty [option ...]
DESCRIPTIONbrltty is a background process (daemon) which provides access to the
console screen (when in text mode) for a blind person using a refresh‐
able braille display. It drives the braille display, and provides com‐
plete screen review functionality. Some speech capability has also
been incorporated.
OPTIONS
Options can be passed to brltty in a number of ways. From most to
least influential, these are:
1. Command Line Options
2. Boot Parameters
3. Environment Variables (if the -E (--environment-variables) option
is in effect)
4. The Configuration File
5. Built-in Defaults
Command Line Options
The options are processed sequentially from left to right. If an
option is specified more than once, or in case of a conflict, the
rightmost specification takes precedence.
The following options are supported:
-a table (--attributes-table=)
The path to the attributes translation table. Relative paths
are anchored at /etc/brltty/. The .tbl extension is optional.
The built-in default is attributes.tbl.
-b driver,...|auto (--braille-driver=)
The driver for the braille display (see Driver Specification).
The built-in default is the first braille driver which was con‐
figured in at build-time.
-c table (--contraction-table=)
The path to the contraction table. Relative paths are anchored
at /etc/brltty/. The .ctb extension is optional.
-d device,... (--braille-device=)
The device to which the braille display is connected. The
built-in default is the primary (first) serial port of the sys‐
tem.
The general form of a braille device specification is quali‐
fier:data. For backward compatibility with earlier releases, if
the qualifier is omitted then serial: is assumed. The following
device types are supported:
Bluetooth
For a bluetooth device, specify bluez:address. The
address must be six two-digit hexadecimal numbers sepa‐
rated by colons, e.g. 01:23:45:67:89:AB.
Serial For a serial device, specify serial:/path/to/device. The
serial: qualifier is optional (for backward compatibil‐
ity). If a relative path is given then it's anchored at
/dev/ (the usual location where devices are defined on a
Unix-like system). The following device specifications
all refer to the primary serial device on Linux:
serial:/dev/ttyS0, serial:ttyS0, /dev/ttyS0, ttyS0.
USB For a USB device, specify usb:. brltty will search for
the first USB device which matches the braille display
driver being used. If this is inadequate, e.g. if you
have more than one USB braille display which requires the
same driver, then you can refine the device specification
by appending the serial number of the display to it, e.g.
usb:12345. N.B.: The "identification by serial number"
feature doesn't work for some models because some manu‐
facturers either don't set the USB serial number descrip‐
tor at all or do set it but not to a unique value.
A comma-delimited list of braille devices may be specified. If
this is done then autodetection is performed on each listed
device in sequence. This feature is particularly useful if you
have a braille display with more than one interrface, e.g. both
a serial and a USB port.
-e (--standard-error)
Write logs to standard error rather than to the system log (use‐
ful for debugging).
-f file (--configuration-file=)
The path to the configuration file. Relative paths are anchored
at the current working directory. The built-in default is
/etc/brltty.conf.
-h (--help)
Print a command line usage summary and then exit.
-l level (--log-level=)
The minimum severity level for messages written to the log. Any
of the following numbers, or any abbreviation of their corre‐
sponding names, may be specified:
0 emergency
1 alert
2 critical
3 error
4 warning
5 notice
6 information
7 debug
The built-in default is notice.
-m device (--midi-device=)
The device to use for the Musical Instrument Digital Interface.
For ALSA it's client:port, where each may be either a number or
a case-sensitive substring of its name. For other interfaces
it's the full path to an appropriate system device. The built-
in default is:
Linux/ALSA the first available MIDI output port
Linux/OSS /dev/sequencer
-n (--no-daemon)
Remain in the foreground (useful for debugging).
-p device (--pcm-device=)
The device to use for digital audio. For ALSA it's name[:argu‐
ment,...]. For other interfaces it's the full path to an appro‐
priate system device. The built-in default is:
FreeBSD /dev/dsp
Linux/ALSA hw:0,0
Linux/OSS /dev/dsp
NetBSD /dev/audio
OpenBSD /dev/audio
Qnx the preferred PCM output device
Solaris /dev/audio
-q (--quiet)
Suppress the start-up messages. This is done by reducing the
default log level (see the -l (--log-level=) option) to warning
(information if either -v (--verify) or -V (--version) is also
specified).
-s driver,...|auto (--speech-driver=)
The driver for the speech synthesizer (see Driver Specifica‐
tion). The built-in default is the first speech driver which
was configured in at build-time.
-t table (--text-table=)
The path to the text translation table. Relative paths are
anchored at /etc/brltty/. The .tbl extension is optional. For
a simple file name, the text. prefix is optional. The built-in
default is text.nabcc.tbl (the North American Braille Computer
Code).
-v (--verify)
Print the start-up messages and then exit. This always includes
the versions of brltty itself, the server side of its applica‐
tion programming interface, and each of the selected braille and
speech drivers. If the -q (--quiet) option isn't also specified
then it also includes copyright information as well as the val‐
ues of the options after all sources have been considered. If
more than one braille driver and/or more than one braille device
has been specified then braille display autodetection is per‐
formed. If more than one speech driver has been specified then
speech synthesizer autodetection is performed.
-A name=value,... (--api-parameters=)
Parameters for the application programming interface. If the
same parameter is specified more than once then the rightmost
specification is used. Parameter names may be abbreviated.
-B [driver:]name=value,... (--braille-parameters=)
Parameters for the braille display driver. If the same parame‐
ter is specified more than once then the rightmost specification
is used. Parameter names may be abbreviated. If a parameter
assignment is qualified with a driver identification code then
it's only processed if that braille display driver is being
used.
-E (--environment-variables)
Recognize environment variables.
-F fifo (--speech-fifo=)
The FIFO which gives other applications access to brltty's
speech driver. It's created at start-up and removed at termina‐
tion. Relative paths are anchored at /etc/brltty/. The built-
in default is that no FIFO is created.
-M csecs (--message-delay=)
The message hold time in hundredths of a second. The built-in
default is 400 (4 seconds).
-N (--no-api)
Don't start the application programming interface.
-P file (--pid-file=)
The full path to the process identifier file. If this option is
supplied, brltty writes its process identifier (pid) into the
specified file at start-up. The file is removed when brltty
terminates.
-S [driver:]name=value,... (--speech-parameters=)
Parameters for the speech synthesizer driver. If the same
parameter is specified more than once then the rightmost speci‐
fication is used. Parameter names may be abbreviated. If a
parameter assignment is qualified with a driver identification
code then it's only processed if that speech synthesizer driver
is being used.
-U csecs (--update-interval=)
The braille window update interval in hundredths of a second.
The built-in default is 4 (25 times per second).
-V (--version)
Print the versions of brltty itself, the server side of its
application programming interface, and those drivers which were
configured in at build-time, and then exit. If the -q (--quiet)
option isn't also specified then also print copyright informa‐
tion.
-X name=value,... (--screen-parameters=)
Parameters for the screen driver. If the same parameter is
specified more than once then the rightmost specification is
used. Parameter names may be abbreviated.
Environment Variables
The following environment variables are recognized if the -E (--envi‐
ronment-variables) option is specified:
BRLTTY_API_PARAMETERS=name=value,...
Parameters for the application programming interface. See the
-A (--api-parameters=) option for details.
BRLTTY_ATTRIBUTES_TABLE=table
The attributes translation table. See the -a (--attributes-ta‐
ble=) option for details.
BRLTTY_BRAILLE_DEVICE=device,...
The device to which the braille display is connected. See the
-d (--braille-device=) option for details.
BRLTTY_BRAILLE_DRIVER=driver,...|auto
The driver for the braille display. See the -b (--braille-
driver=) option for details.
BRLTTY_BRAILLE_PARAMETERS=[driver:]name=value,...
Parameters for the braille display driver. See the -B
(--braille-parameters=) option for details.
BRLTTY_CONFIGURATION_FILE=file
The configuration file. See the -f (--configuration-file=)
option for details.
BRLTTY_CONTRACTION_TABLE=table
The contraction table. See the -c (--contraction-table=) option
for details.
BRLTTY_MIDI_DEVICE=device
The device to use for the Musical Instrument Digital Interface.
See the -m (--midi-device=) option for details.
BRLTTY_PCM_DEVICE=device
The device to use for digital audio. See the -p (--pcm-device=)
option for details.
BRLTTY_SCREEN_PARAMETERS=name=value,...
Parameters for the screen driver. See the -X (--screen-parame‐
ters=) option for details.
BRLTTY_SPEECH_DRIVER=driver,...|auto
The driver for the speech synthesizer. See the -s (--speech-
driver=) option for details.
BRLTTY_SPEECH_FIFO=fifo
The FIFO which gives other applications access to brltty's
speech driver. See the -F (--speech-fifo=) option for details.
BRLTTY_SPEECH_PARAMETERS=[driver:]name=value,...
Parameters for the speech synthesizer driver. See the -S
(--speech-parameters=) option for details.
BRLTTY_TEXT_TABLE=table
The text translation table. See the -t (--text-table=) option
for details.
The Configuration File
Blank lines are ignored. If the character # occurs on any line then
all characters from it to the end of that line are treated as a com‐
ment.
The following configuration directives are supported:
api-parameters name=value,...
Parameters for the application programming interface. See the
-A (--api-parameters=) option for details.
attributes-table table
The attributes translation table. See the -a (--attributes-ta‐
ble=) option for details.
braille-device device,...
The device to which the braille display is connected. See the
-d (--braille-device=) option for details.
braille-driver driver,...|auto
The driver for the braille display. See the -b (--braille-
driver=) option for details.
braille-parameters [driver:]name=value,...
Parameters for the braille display driver. See the -B
(--braille-parameters=) option for details.
contraction-table table
The contraction table. See the -c (--contraction-table=) option
for details.
midi-device device
The device to use for the Musical Instrument Digital Interface.
See the -m (--midi-device=) option for details.
pcm-device device
The device to use for digital audio. See the -p (--pcm-device=)
option for details.
screen-parameters name=value,...
Parameters for the screen driver. See the -X (--screen-parame‐
ters=) option for details.
speech-driver driver,...|auto
The driver for the speech synthesizer. See the -s (--speech-
driver=) option for details.
speech-fifo fifo
The FIFO which gives other applications access to brltty's
speech driver. See the -F (--speech-fifo=) option for details.
speech-parameters [driver:]name=value,...
Parameters for the speech synthesizer driver. See the -S
(--speech-parameters=) option for details.
text-table table
The text translation table. See the -t (--text-table=) option
for details.
Driver Specification
A braille display or speech synthesizer driver must be specified via
its identification code:
al Alva
at Albatross
bl BrailleLite
bn BrailleNote
cb CombiBraille
ec EcoBraille
es ExternalSpeech
eu EuroBraille
fl FestivalLite
fs FreedomScientific
fv Festival
gs GenericSay
ht HandyTech
lt LogText
mb MultiBraille
md MDV
mn MiniBraille
mp Mikropuhe
no no driver
pm Papenmeier
th Theta
ts Telesensory Systems Inc.
tt TTY
va Vario/RBT (emulation 1)
vd VideoBraille
vh Vario/RBT (emulation 2)
vo Voyager
vr Virtual
vs VisioBraille
vv ViaVoice
xw XWindow
A comma-delimited list of drivers may be specified. If this is
done then autodetection is performed using each listed driver in
sequence. You may need to experiment in order to determine the
most reliable order since some drivers autodetect better than
others.
If the single word auto is specified then autodetection is per‐
formed using only those drivers which are known to be reliable
for this purpose.
SEE ALSO
For full documentation, see brltty's on-line manual at
[http://mielke.cc/brltty/doc/Manual-HTML/Manual.html].
brltty 3.7.2 December 2005 BRLTTY(1)
