#!/usr/bin/env bash
#
#
#Write characters specified in argv[1] to file argv[2] unless file exists
#Must be run as root
#Length determined by $RANDOM % 94
#

function helper(){
    echo "Syntax:
$0 [ r | n ] output-file
$0 c char-to-fill-with output-file
Where r = 'random chars' and n = 'nul values'
If using 'c', only one character may be specified
Output must not already exist
Command must be run as root"
    exit
}

if (( $# < 2 )) || [ -f ${!#} ] || [ "$(whoami)" != "root" ]; then
    helper
fi

LEN=`echo $1|wc -c`
SIZE=$(($RANDOM % 94))

if [ "$1" == "r" ]; then
    dd if=/dev/urandom of=$2 count=$SIZE
elif [ "$1" == "n" ]; then
    dd if=/dev/zero of=$2 count=$SIZE
elif [ "$LEN" == "2" ] && (( $# == 3 )); then
    # One block = 512 chars
    for (( a=0;a<$SIZE*512;a++ )); do
	echo "$2" >> $3
    done
else helper
fi