automate Sway window manager with just command runner

In this post I will show how to automate common Sway (or any desktop) commands with the just command runner.

The problem and the solution

I like cli tools. Well that's an understatement. I love them. The problem is you need to remember a lot of commands - with sometime bizarre and hard to remember syntax - to increase your productivity while working on daily tasks. What is even worse, some of useful commands are not used often enough to remember them easily (also: it's not helping that human brain is harder to train as it's getting older).

Sway window manager main settings command is no exception here, but we can tackle this with the just command runner. It helps shorten common commands and adds command description.

What is Sway ?

As it stands on Sway home page

Sway is a tiling Wayland compositor and a drop-in replacement for the i3 window manager

Sway is a special kind of keyboard oriented window manager using idea of tiles instead of well known resizable windows. Whenever you open an app it takes half a screen, but you can arrange 'windows' in tiles, tabs or even make a floating window (just like in traditional window managers).

What is just ?

Just is a convenient and lightweight way (written in rustlang) of running project specific commands without creating custom bash scripts. It has make like syntax, but scripts could be written in any lang. Additionally it can read variables from .env files and has many more features. You can read about them in the just book.

How to use just

Let's start with somethng basic. I do assume you already installed just.

First create the justfile in your home directory and put following content in there:

# print this help
help:
    just -l

# list files with details
ls:
   ls -lah

now type in your home dir shell

just

you will see th result

~$ just

just -l
Available recipes:
    help # print this help
    ls   # list files with details
~$ 

How to automate ?

Ok assuming you know some just basics you are ready to write your own justfile. I do reccomend to write it directly into your user home dir.

after filling justfile with your commands, it will be as easy as writing

just your_command

to invoke any command (which is maybe a multiline script).

Now let's see my just commands

just

will result in the following output

just --list
Available recipes:
    day                  # light display for day
    disable display      # disable display output
    displays             # list available displays
    enable display="all" # enable *display* output
    evening              # dim display for evening view
    get_off              # shutdowns computer
    help                 # disply this help
    laptop               # disable all display outputs except main laptop display
    night                # dim display for night view
    not_laptop           # disable laptop display outputs and enable external displays
    showkeys             # show typed keys on the screen

As you can see my main use of just commands is display output and dim management.

Very common and atomic commands are deserving their own key binding (can be defined in ~/.config/sway/config), wherease just usage is fitting more for less frequent or compound commands.

I keep my justfile source code in my github config repo, Currenlty it looks like this:

# disply this help
help:
    just --list

# shutdowns computer
get_off:
   shutdown -h now

# list available displays
displays:
   swaymsg -t get_outputs | jq '.[] | .name'

# enable *display* output
enable display="all":
    #!/usr/bin/env bash
    case {{display}} in
        "all")
            for i in `swaymsg -t get_outputs | jq '.[] | .name'`;
            do
             swaymsg output $i enable
            done
            swaymsg output DP-5 pos 0 0
            swaymsg output DP-7 pos 0 1200
            ;;
        "laptop")
            for i in `swaymsg -t get_outputs | jq '.[] | .name'`;
            do
            if [[ $i == '"eDP-1"' ]]; then
              swaymsg output $i enable
            else
              swaymsg output $i disable
            fi
            done
            ;;
        *)
            swaymsg output {{display}} enable
            ;;
    esac

# disable display output
disable display:
   swaymsg output {{display}} disable


# disable all display outputs except main laptop display
laptop:
   #!/usr/bin/env bash
   for i in `swaymsg -t get_outputs | jq '.[] | .name'`;
   do
      if [[ $i == '"eDP-1"' ]]; then
         swaymsg output $i enable
      else
         swaymsg output $i disable
      fi
   done

# disable laptop display outputs and enable external displays
not_laptop:
   #!/usr/bin/env bash
   for i in `swaymsg -t get_outputs | jq '.[] | .name'`;
   do
      if [[ $i != '"eDP-1"' ]]; then
         swaymsg output $i enable
      else
         swaymsg output $i disable
      fi
   done

# dim display for night view
night:
   light -S 1

# dim display for evening view
evening:
   light -S 4

#light display for day
day:
   light -S 25

#show typed keys on the screen
showkeys:
   wshowkeys -a bottom

Closing remarks

The thing is you don't need to be linux freak to use just. You may use it to manage your mainstream operating system as well (including the evil/spying one). You can automate common operations like backups, remote server commands (as long as they're easy enough to not use proper management tool like Ansible or Chef) and also for changing your enviroment for certain work modes, e.g. I am using project specific just dev command to start all required docker containers, while working on certain group of projects.