When I was working on a Terminal, I used to type lots of cd and cd .. to go back and forth the directory. Too often, when I went to deep into the directory hierarchy, I got to type multiple times cd .. just to move up to parents, or a long command like cd ../../../../../.
I got frustrated every freaking time doing this, so I thought of an more easy way to type once and it got me to the correct directory up in the hierarchy, I call the alias two-dots.
# Add this into your ~/.bashrc or ~/.zshrc
function back() { for x in {1..${1:-1}}; do cd ..; done }
alias ..='back'
How it works:
# Suppose your are in
$> cd some/project/that/has/a/very/deep/directory/structure
structure $>
# Say you need to go back to 'that' directory.
# Since it requires 6 times typing `cd ..` to achieve this or just
$> .. 6
that $>
Grokking Hard 