cd ../../../foo/bar is boring. 'up 3 foo/bar'

up function

up () {
        if [ "$#" -eq 0 ]
        then
                echo "Up to where?"
                return 1
        fi
        times=$1 
        target="$2" 
        while [ $times -gt 0 ]
        do
                target="../$target" 
                times=$((times - 1)) 
        done
        cd $target
}