Zsh Tips 2: Directory Stacks

What we do for ourselves dies with us. What we do for others remains forever.
—Albert Pike

Table of contents

• Introduction
• Saving
• Restoring
• Closing remarks

Introduction

Last time, I wrote about aliases and functions, and how to use them to enhance your command line experience. In this article, I will talk about a simple way to save and restore directory stacks.

Every time I change directory through cd, I use pushd to save that directory on that directory stack. This enables me to go back to the previous directory, before I call pushd, with the use of popd. The command dirs, displays the current value of the directory stack.

First, let’s define our helpers:

function d () { pushd $@ }
function - () { popd }
function ds () { dirs -l $@ }

Then, consider this session:

% d ~/Downloads
% ds -v
0       /home/ebzzry/Downloads
% d /etc/nixos
% d /tmp
% ds -v
0       /tmp
1       /etc/nixos
2       /home/ebzzry/Downloads

At this point I have three directories in the directory stack. If I run popd:

% -

I will get the following:

% pwd
/etc/nixos
% ds -v
0       /etc/nixos
1       /home/ebzzry/Downloads

Saving

Directory stacks allows us to move through the trees that we are working on currently. Pushing to the directory stack permits us to visit a directory, wherein we will perform actions there, then go back to the last one through popping, with ease.

However, when I create a new shell, that stack is lost. I use exec to reload my Zsh session, to ensure that my config files are read from scratch.

% exec zsh

But doing so, removes the stack that I have built. To work this around, I have a function that saves the directory stack of the current session:

function z! () {
  dirs -lv | awk -F '\t' '{print $2}' | tac >! $HOME/.z
  exec zsh
}

Running z! will save the contents of the current stack, and restart the shell:

% pwd
/home/ebzzry
% d /etc/nixos
% d ~/Downloads
% d /var/lib
% z!

Restoring

To accompany z!, I have a function that restores the saved directory stack:

function z+ () {
  if [[ -f $HOME/.z ]]; then
      local pwd=$PWD

      while read -r line; do
        pushd "$line"
      done < $HOME/.z

      pushd $pwd
  fi
}

To restore the saved directory stack, on the current session, or a new separate instance, run:

% z+
% ds -v
0       /var/lib
1       /home/ebzzry/Downloads
2       /etc/nixos
3       /home/ebzzry

Closing remarks

I use directory stacks as a way to save the directories that I interact with so that it will be easier to restore to a previous working state. Having these two helper commands makes it even more enjoyable to work in the command line. For the rest of the definitions, visit the repo here.