#!/bin/bash

dirname=files
filename=file_0
counter=0

while [ -d "$dirname" ]
do
	dirname="${dirname%_*}"_$counter
	(( counter++ ))
done

mkdir "$dirname"
cd "$dirname"
counter=0

for a in {0..9}
do
	while [ -e "$filename" ]
	do
		filename="${filename%_*}"_$counter
		(( counter++ ))
	done
	
	touch "$filename"
done