filernd

while getopts ":p:l:" arg; do
  case $arg in
    p) prefix=$OPTARG;;
    l) length=$OPTARG;;
  esac
done
if [[ $* = *"-d"* ]]
then
	doDir=true
else
	doDir=false
fi

if [[ -z $prefix || -z $length ]]; then
	echo "Usage: filernd -l (new length of files) -p (prefix of files)"
	echo "set -d to include directories"
	exit 1
fi

if [[ $length -le 0 ]];
then 
	echo "Length cannot be less than 0"
	exit 1

fi
if [[ $prefix -le -1 ]];
then 
	echo "Prefix cannot be cannot be negative"
	exit 1

fi

same=0
for i in *;
do
	set=1
	while [ "$set" -eq 1 ]
	do
		set=0
		random=$(head /dev/urandom | tr -dc A-Za-z0-9 | head -c $(($length-$prefix)) )
		fileprefix=$(echo ${i::$prefix})
		if [[ $i == *.* ]]
		then
			end=$(echo $i |awk -F"." '{print "." $NF}')
			newfile="$random""$end"
		else
			newfile="$random"
		fi
		towrite="$fileprefix""$newfile"
		if [ -f "$towrite" ] || [ -d "$towrite" ]
		then
			echo "Same name detected. Trying again"
			set=1
			((same++))
			if [[ $same -gt 10000 ]]
			then	
				echo -e "\nGot file exists 10,000 times in a row"
				echo "We may have run out of file names." 
				echo "Try setting the length a bit higher. Exiting"
				exit
			fi
		else
			if [ -d "$i" ] && [[ $doDir = true ]]
			then
				mv "$i" "$towrite"
				echo "Changing directory $i to $towrite"
			elif [ ! -d "$i" ]
			then
				mv "$i" "$towrite"
				echo "Changing file $i to $towrite"
			fi
			same=0
		fi
	done
done