Control Hubs: Bringing It All Together - Smart Home Automation with Linux and Raspberry Pi - page 222

say : This is the most interesting abstraction, despite being the simplest, because this
queries the default voice (stored as a name in $MINBASE/etc/defaults/festvox , if present)
and invokes festival . When called on behalf of a specific user, it uses their customized
voice settings. There is also a sayfile variant for longer phrases using Festival's more
efficient --tss argument.
announce : This is an important extension because its context is different. Namely, it's used
for announcements to the house that something (important) is happening. It wraps the call
to say by playing a chime sound and lowers the volume of any music that might be playing,
before making the announcement and returning the volume levels to normal. Because
of the importance of such messages, the device should generally be different from that of
mp3player to prevent audio device conflicts in some systems. 3 In the worst cases, this can
require using a second sound card or making use of the sound card in an external machine
that generally has no use for audio, such as a wall panel. The wavplayer is often configured
to use this same device.

report : This produces preformatted information about train times, time, date, and
calendar. It is a useful way of creating a homogeneous way of presenting this data, and
eliminating injection attacks.

tweet : This is a way of publishing an announcement via microblogging site Twitter. This can be
used by multiple users in the house, as it queries a set of stored credentials for each user in
$MINBASE/etc/users/[username]/external/twitter .
irsend : This is a means to send predetermined infrared remote-control codes to the
connected IR transmitter. It will then be picked up by any sensor in range. For this reason,
most IR-enabled equipment is held in Node0 where a single transmitter can service them all.
It takes two arguments, the name of the equipment and the message that needs to be sent,
and retrieves the code from a file held in $MINBASE/etc/ir/[equipment]/codes/[command] .
The format of the data in this file is governed by the name in
$MINBASE/etc/ir/[equipment]/method .
The <device> in each case will generally be default to indicate the default output stream, which is the set of
devices attached to the server machine, mentioned earlier.

N Most Bearskin commands are controlled by killing and restarting the Linux process. This means that in many
cases you cannot amend the mp3player process from a user who didn't initiate it. That is, if you began MP3 playback
using the web interface, you can't stop the music using Cosmic or the command line, unless the governing user has the
user privileges to do so.

Note

Monexec
Monexec is a script that is called manually by the various Bearskin commands mentioned earlier to log each action.
When the CD player is started, for example, the cdplayer script calls the following:

$MINBASE/bin/monexec cdplayer play

!LWAYSDETERMINEWHETHERYOURSOUNDCARDANDITSDRIVERSALLOWYOUTOPLAYAUDIOFROMSEVERALAPPLICATIONSATONCE