pad.sh

#!/bin/bash

# This is a WTF Bash script licensed under the WTFPL license (what else?).

# WTF:
#   1. Watching http://youtu.be/lTx3G6h2xyA
#   2. "Hey, what a nice device..."
#   3. See http://amzn.com/B0046ZIZO8
#   4. "Doh! $159! Way too expensive for a broke student... :/"
#   5. ...
#   6. "Everything is possible with Bash!"
#   7. End up with this script

# Usage:
#   - no args: interactive mode
#   - or, pass in a file as the first arg to read it char by char

# Examples:
#   - ./pad.sh # then use your keyboard as a (kind of) pad
#   - ./pad.sh /dev/random # then move your mouse like a psycho to get some entropy
#   - ./pad.sh /dev/urandom # to produce some pseudo-random garbage sound
#   - ./pad.sh pad.sh # how meta

# change to your sweet sounds directory
DIR=/usr/lib/libreoffice/share/gallery/sounds

# max simultaneous sounds playing
# (especially useful when input file is /dev/urandom for instance)
MAX=30

###

set -eu
stty -echo

trap bye INT TERM

bye() {
    local stopped=$(date +%s)
    local time=$(($stopped - $started))
    echo "Played ${total} sounds for ${time} seconds."
    exit 0
}

playing() {
    ps --no-headers -o pid --ppid=$$ | wc -w # number of children
}

###

declare -a sounds=($(ls -1 $DIR))
count=${#sounds[@]}

started=$(date +%s)
total=0

[[ $# -eq 1 && -r "$1" ]] && input=$1 || input=
[ "$input" ] && exec 3<"$input" || exec 3<&0

while read -n 1 key; do
    code=$(printf "%d" "'$key'") # ASCII code
    code=$(($code % $count))
    sound=${sounds[$code]}

    while [ $(playing) -ge $MAX ]; do sleep .1; done
    echo "($(playing)) ${sound} [${key}]"
    aplay --quiet "${DIR}/${sound}" &

    total=$(($total + 1))
done <&3 # this is not a smiley