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 configured 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 system.

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 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 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.

-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).

-s driver,...|auto (--speech-driver=)

The driver for the speech synthesizer (see Driver Specification). 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 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 copyright information as well as 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.

-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 fifo (--speech-fifo=)

The FIFO which gives other applications access to brltty's speech driver. It's created at start-up and removed at termination. 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 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.

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 translation 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_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_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.

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 translation 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.

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-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.

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 performed using only those drivers which are known to be reliable for this purpose.