PulseAudio volume control in Bash

volume.sh

#!/bin/bash                                                                                                                                                                               

SINK=0 # default sink
STEP=10 # %
POINTS=`pacmd list-sinks | awk '/volume steps/ {print $3}'`
ONE_PERCENT=`expr $POINTS / 100`
ISMUTED=`pacmd list-sinks | awk '/mute/ {print $2}' `
CURRENT_VOLUME=;

function live {
    live_help
    while read -sN1 key # 1 char (not delimiter), silent
    do
    # catch multi-char special key sequences

        read -sN1 -t 0.0001 k1
        read -sN1 -t 0.0001 k2
        read -sN1 -t 0.0001 k3

        key+=${k1}${k2}${k3}

        case "$key" in

            $'\e[A' | $'\e0A')
                volume_sign +
            ;;
            $'\e[B' | $'\e0B')
                volume_sign -
            ;;
        esac

    done
}

function live_help {
    echo "
Use your up down arow keys to adjust volume
    Ctrl-c to quit
";
}

function volume {

    if [ $1 -gt 99 ]; then
        VOLUME=$POINTS
    elif [ 0 -gt $1 ]; then
        VOLUME=0
    else
        VOLUME=`expr $ONE_PERCENT \* $1`
    fi

    echo "set volume $VOLUME, $1%"

    pacmd set-sink-volume $SINK $VOLUME > /dev/null
}
unction get_volume {
    CURRENT_VOLUME=`pacmd list-sinks | awk '/\tvolume:/ {print $3}' | sed 's/%//'`
}


function volume_sign {
    get_volume
    volume $( expr $CURRENT_VOLUME $1 $STEP )
}

function mute {
    pacmd set-sink-mute $SINK $1 > /dev/null
}

function toggle {
    if [ "$ISMUTED" = "yes" ]; then
        mute 0
    else
        mute 1
    fi
}


function help {
    echo "
  Please provide correct input
   default sink: $SINK

    mute
    unmute
    toggle  - toggle between mute states

    +, up   - volume up   by $STEP
    -, down - volume down by $STEP

    live    - enables live mode in wich every arow press modifies volume

"
}

# main 

case "$1" in
    "mute")
        mute 1
    ;;
    "unmute")
        mute 0
    ;;                                                                                                                                                                                    
    "toggle")
        toggle
    ;;
    "live")
        live
    ;;
    "+" | "up" )
        volume_sign +
    ;;
    "-" | "down" )
        volume_sign -
    ;;
    100 | [1-9][0-9] | [1-9] )
        volume $1
    ;;
    *)
        help
    ;;
esac