pipes.sh

    #!/bin/sh

        declare -i f=75 s=13 r=2000 t=0 c=1 n=0 l=0
        declare -ir w=$(tput cols) h=$(tput lines)
        declare -i x=$((w/2)) y=$((h/2))
        declare -ar v=( [00]="\x83" [01]="\x8f" [03]="\x93"
                [10]="\x9b" [11]="\x81" [12]="\x93"
                [21]="\x97" [22]="\x83" [23]="\x9b"
                [30]="\x97" [32]="\x8f" [33]="\x81" )

        OPTIND=1
        while getopts "f:s:r:h" arg; do
        case $arg in
            f) ((f=($OPTARG>19 && $OPTARG<101)?$OPTARG:$f));;
            s) ((s=($OPTARG>4 && $OPTARG<16 )?$OPTARG:$s));;
            r) ((r=($OPTARG>0)?$OPTARG:$r));;
            h) echo -e "Usage: pipes [OPTION]..."
                echo -e "Animated pipes terminal screensaver.\n"
                echo -e " -f [20-100]\tframerate (D=75)."
                echo -e " -s [5-15]\tprobability of a straight fitting (D=13)."
                echo -e " -r LIMIT\treset after x characters (D=2000)."
                echo -e " -h\t\thelp (this screen).\n"
                exit 0;;
            esac
        done

    tput smcup
    tput reset
    tput civis
    while true; do
            # New position:
            (($l%2)) && ((x+=($l==1)?1:-1))
            ((!($l%2))) && ((y+=($l==2)?1:-1))

            # Loop on edges (change color on loop):
            ((c=($x>$w || $x<0 || $y>$h || $y<0)?($RANDOM%7):$c))
            ((x=($x>$w)?0:(($x<0)?$w:$x)))
            ((y=($y>$h)?0:(($y<0)?$h:$y)))

            # New random direction:
            ((n=$RANDOM%$s-1))
            ((n=($n>1||$n==0)?$l:$l+$n))
            ((n=($n<0)?3:$n%4))

            # Print:
            tput cup $y $x
            printf "\033[1;3${c}m\xe2\x94${v[$l$n]}"
            (($t>$r)) && tput reset && tput civis && t=0 || ((t++))
            l=$n
    done
    tput rmcup
    clear