#!/bin/bash
LEVEL=$1
for ((i = 0; i < LEVEL; i++)); do
  echo $i
  CDIR=../$CDIR
done
cd $CDIR
echo "You are in: "$PWD
sh=$(which $SHELL)
exec $sh

root@yourdomain:~/shell/shell-docs/scripts# pwd
/root/shell/shell-docs/scripts
root@yourdomain:~/shell/shell-docs/scripts# bash up.sh 
You are in: /root
root@yourdomain:~#
root@yourdomain:~/shell/shell-docs/scripts# bash up.sh 1
0
You are in: /root/shell/shell-docs
root@yourdomain:~/shell/shell-docs/scripts# bash up.sh 2
0
1
You are in: /root/shell