#!/bin/sh 
# Sound Manager 
#

### BEGIN INIT INFO
# Provides:          soundmanager
# Required-Start:    $local_fs $remote_fs $syslog $network
# Required-Stop:     $local_fs $remote_fs $syslog $network
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Sound Manager
# Description:       Start the Sound Manager daemon
### END INIT INFO


PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/entity/bin //designate the various path's so that the shell knows where to look for executable's
data_dir=/usr/local/entity/project //designate a location where the shell can store information (does not seem to be used in the script)
SOUNDMANAGER=bmsoundmanager //give the bmsoundmanager a variable or an alias in this case "SOUNDMANAGER" the bmsoundmanager 
                            //is a program within entity/bin which controls various aspects
                            //of the sound system, it is an extension of SoundManagerAlsa

 
start() { //the "start" function, first statement in the case statement 
    echo -n "Starting Sound Manager:             " //print statement, will not output the trailing newline
    # Enable audio amplifier mode input
    echo 107 > /sys/class/gpio/export //not completely sure what this does, it might compare the value 107 to a value found in the export directory
    # Mute the amplifier
    echo 0 > /sys/class/gpio/gpio107/value //again not completely sure what this does
      ( ${SOUNDMANAGER} -q -n& ) && echo '[ OK ]' || echo '[FAIL]' //start the bmsoundmanager and feed it the
                                                                   //conditions -q (quiet = true: debug output is muted) and -n (detach = false: do not run as a daemon) 
                                                                   //&& means 'and' while || means 'or'
                                                                    //I am not sure how the program knows to echo OK versus FAIL
}

 
 
stop() { //the "stop" function, second statement in the case statement
    echo -n "Stopping Sound Manager:             " //print statement, will not output the trailing newline
    killall -HUP ${SOUNDMANAGER} //stops the program from running; however, H U P aren't in the man pages for the killall command so I am not sure what they do
}

//Here we have the case statement or the conditional logic. The first condition being that a user entered the command: 'start' and the second being
//that the user entered 'stop' when running the shell. 
case "$1" in
"start")
        start
        ;;
"stop")
        stop
        echo "OK"
    ;;
reload|restart)
        stop
        sleep 1
        start
    ;;
*)
    echo "$0: unknown argument $1." >&2;
    ;;
esac

#