Small function allowing to use `..` to go back a level. add a dot for each subsequent up. Simply source the file in bashrc.

up.sh

#!/bin/bash

##
# This script allow to use a shorthand to navigate the directory structure.
# To use this script, simply source this script in your ~/.bashrc
# 
# Examples:
# `..`             : Move up by 1 directory.
# `....`           : Move up by 3 directory.
# `.../hello_world`: Move up by 2 directory, then move into the directory `hello_world`.
##

shopt -s extdebug

function _up() {
	# Only execute if the command starts with '..'
	if [ "${BASH_COMMAND:0:2}" == ".." ]; then
		# Tab completion refire the trap with the last command since it wasn't consumed.
		# Therefore this allows to consume the last command.
		[ "${BASH_COMMAND}" == "${_up_kill}" ] && \
			_up_kill="" && \
			return

		# Parse the command.
		precut=$(echo "${BASH_COMMAND}" | sed -E 's#^(\.*)\/?(.*)#\1;\2#')
		up=$(echo ${precut} | cut -d ';' -f1)
		postpath=$(echo ${precut} | cut -d ';' -f2)

		# Up based on the number of dot in the command.
		let "count = ${#up} - 2"
		for i in $(seq 0 ${count}); do
			cd ..
		done
		# Change directory to post up path
		[ "${postpath}" != "" ] && cd ${postpath}

		_up_kill="${BASH_COMMAND}"
		return 1
	fi
}

trap '_up' DEBUG