prezto/functions/directory.zsh

setopt auto_cd              # Auto cd to a directory without typing cd.
setopt auto_pushd           # Push the old directory onto the stack on cd.
setopt pushd_ignore_dups    # Don't store duplicates in the stack.
setopt cdable_vars          # Change directory to a path stored in a variable.
setopt auto_name_dirs       # Auto add variable-stored paths to ~ list.
setopt multios              # Write to multiple descriptors.

alias ..='cd ..'
alias cd..='cd ..'
alias cd...='cd ../..'
alias cd....='cd ../../..'
alias cd.....='cd ../../../..'
alias cd/='cd /'

alias 1='cd -'
alias 2='cd +2'
alias 3='cd +3'
alias 4='cd +4'
alias 5='cd +5'
alias 6='cd +6'
alias 7='cd +7'
alias 8='cd +8'
alias 9='cd +9'

cd () {
  if   [[ "x$*" == "x..." ]]; then
    cd ../..
  elif [[ "x$*" == "x...." ]]; then
    cd ../../..
  elif [[ "x$*" == "x....." ]]; then
    cd ../../..
  elif [[ "x$*" == "x......" ]]; then
    cd ../../../..
  else
    builtin cd "$@"
  fi
}