Jump to a directory up the tree by name

xs.fish

function xs
    # go to /home/chanux/down from /home/chanux/down/the/rabbithole/we/go
    # by typing xs down
    # you might also like za http://wp.me/p1rVu-bO
    set matches (echo "$PWD" | grep -o "/$argv[1][^/]*/" | wc -l)
    if test $matches -gt 1
        cd (echo $PWD | sed "s:/$argv[1]/.*:/:")$argv[1]
    else if echo "$PWD" | grep -q "/$argv[1]/"; test $status -eq 0
        cd (echo $PWD | sed "s:$argv[1].*::")$argv[1]
    end
end

xs.sh

xs() {
    # For BASH and ZSH
    if [[ "$PWD" == */$1/* ]]
    then
        cd ${PWD%$1*}$1
    fi
}

Had this idea while using za today. Quickly implemented for my shell <"><
Not too shabby!

Known bug: If there are multiple directories by the same name, it'd go to the farthest