brltty
refreshable braille display driver for Linux/Unix
Synopsis
brltty
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description
brltty
is a background process (daemon) which provides access to
the console screen (when in text mode) for a blind person
using a refreshable braille display. It drives the braille
display, and provides complete 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
table. Relative paths are anchored at /etc/brltty.
The .atb extension is optional. The built-in default
is attributes.atb.
-b
driver,...|auto
(--braille-driver=)
The driver for the braille
display (see Driver Specification). The built-in default is
auto.
-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
usb:.
The general
form of a braille device specification is
qualifier: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 separated 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 compatibility). 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:
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 manufacturers either don’t set the
USB serial number descriptor 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 (useful 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.
-i name
(--speech-input=)
The file system object (FIFO,
named pipe, named socket, etc) which gives other
applications access to brltty’s speech driver
for text-to-speech conversion. It’s created at
start-up and removed at termination. Relative paths are
anchored at the current working directory. The built-in
default is that the file system object is not created.
-l level
(--log-level=)
The minimum severity level for
messages written to the log. Any of the following numbers,
or any abbreviation of their corresponding 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[:argument,...]. For other
interfaces it’s the full path to an appropriate 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).
-r
(--release-device)
Release the device to which the
braille display is connected when the current screen or
window can’t be read.
-s
driver,...|auto
(--speech-driver=)
The driver for the speech
synthesizer (see Driver Specification). The built-in default
is auto.
-t table
(--text-table=)
The path to the text table.
Relative paths are anchored at /etc/brltty. The
.ttb extension is optional. The built-in default is
nabcc.ttb (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 application
programming interface, and each of the selected braille and
speech drivers. If the -q (--quiet) option
isn’t also specified then it also includes the values
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 performed. If more than one speech driver has been
specified then speech synthesizer autodetection is
performed.
-x driver
(--screen-driver=)
The screen driver. The built-in
default is operating system appropriate.
-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 parameter 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 file
(--preferences-file=)
The path to the preferences
file. Relative paths are anchored at /var/lib/brltty.
The built-in default is brltty.prefs.
-I
(--install-service)
(Windows only) Install
brltty as the BrlAPI service so that it will
be automatically started when the system is booted and so
that applications can know that a BrlAPI server is
running.
-L file
(--log-file=)
The file to which log messages
are written. Relative paths are anchored at the current
working directory. The default is to send log messages to
the system log.
-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.
-R
(--remove-service)
(Windows only) Remove the
BrlAPI service so that brltty will not be
automatically started when the system is booted and so that
applications can know that no BrlAPI server is
running.
-S
[driver:]name=value,...
(--speech-parameters=)
Parameters for the speech
synthesizer driver. If the same parameter 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 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 information.
-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 (--environment-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 table. See the
-a (--attributes-table=) 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_PREFERENCES_FILE=file
The preferences file. See the
-F (--preferences-file=) option for
details.
BRLTTY_RELEASE_DEVICE=on|off
Release the device to which the
braille display is connected when the current screen or
window can’t be read. See the -r
(--release-device) option for details.
BRLTTY_SCREEN_DRIVER=driver
The screen driver. See the
-x (--screen-driver=) option for details.
BRLTTY_SCREEN_PARAMETERS=name=value,...
Parameters for the screen
driver. See the -X (--screen-parameters=)
option for details.
BRLTTY_SPEECH_DRIVER=driver,...|auto
The driver for the speech
synthesizer. See the -s (--speech-driver=)
option for details.
BRLTTY_SPEECH_INPUT=name
The file system object which
gives other applications access to brltty’s
speech driver for text-to-speech conversion. See the
-i (--speech-input=) 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 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 comment.
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 table. See the
-a (--attributes-table=) 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.
The preferences file.
See the -F
(--preferences-file=) option for details.
release-device
on|off
Release the device to which the
braille display is connected when the current screen or
window can’t be read. See the -r
(--release-device) option for details.
screen-driver
driver
The screen driver. See the
-x (--screen-driver=) option for details.
screen-parameters
name=value,...
Parameters for the screen
driver. See the -X (--screen-parameters=)
option for details.
speech-driver
driver,...|auto
The driver for the speech
synthesizer. See the -s (--speech-driver=)
option for details.
speech-input 0me
The file system object which
gives other applications access to brltty’s
speech driver for text-to-speech conversion. See the
-i (--speech-input=) 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 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
ba
BrlAPI
bc
BrailComm
bd
Braudi
bl
BrailleLite
bm
Baum
bn
BrailleNote
cb
CombiBraille
ec
EcoBraille
es
eSpeak
eu
EuroBraille
fl
FestivalLite
fs
FreedomScientific
fv
Festival
gs
GenericSay
hm
HIMS
ht
HandyTech
hw
HumanWare
il
IrisLinux
ir
Iris
lb
Libbraille
lt
LogText
mb
MultiBraille
md
MDV
mn
MiniBraille
mp
Mikropuhe
mt
Metec
no
no driver
np
NinePoint
pg
Pegasus
pm
Papenmeier
sd
SpeechDispatcher
sk
Seika
sw
Swift
th
Theta
tn
TechniBraille Systems Inc.
ts
Telesensory Systems Inc.
tt
TTY
vd
VideoBraille
vo
Voyager, Part232 (serial adapter),
BraillePen/EasyLink
vr
Virtual
vs
VisioBraille
vv
ViaVoice
xs
ExternalSpeech
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
performed 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].