ABCD – a better cd

Unix’s builtin cd command has a very nice feature, “cd minus”:

cd -
   Go back to the direcotry previous to the current one.
   Same as: cd "$OLDPWD"

Let’s make cd better. Let’s extend this functionality, such that:

`cd --`   Go back two directories previous to the current one.
`cd ---`  Go back three directories previous to the current one.

Why stop there? How about cd -4, cd -5 and so on? In the process, of course we want to be backwards-compatible with the fundamental properties of cd:

`cd DIR`  Change to directory DIR
`cd`      Change to $HOME. Same as `cd ~`

To implement this, let’s make use of bash’s building blocks: pushd and popd. Here it is how to do it:

function cd()  {
    local dir="$1";  local old=()
    [[ -z "$dir" ]] && dir="$HOME"
    [[ "$dir" == "-" ]] && dir=-1
    [[ "$dir" == "--" ]] && dir=-2
    [[ "$dir" == "---" ]] && dir=-3
    local head="${dir:0:1}"   # first char of $dir
    if [[ "$head" == "-" ]]; then
        while [[ "$dir" -lt 0 ]]; do
            old+=(`pwd`)
            popd > /dev/null
            let dir=dir+1
        done
        for (( idx="${#old[@]}"-1 ; idx>=0 ; idx-- )); do
            pushd -n "${old[idx]}" > /dev/null
        done
    elif [[ "$head" == "+" ]]; then
        popd "$dir" > /dev/null
    else
        pushd "$dir" > /dev/null
    fi
}

You can simply copy-paste the above in your ~/.bashrc for example.

Examples

Also mention dirs -v and dirs -c

How does the code work

Caveats

1. cd takes two options, -L and -P, related to symlink-following (or not). The above code does not consider that. It always follows symlinks, just like the default behavior of cd.
2. If you have turned on autocd option of Bash v4 (and later), the our own cd is not triggered. It uses the builtin cd always.