coastalwhite/lemurs

Lemurs is a Terminal User Interface (TUI) Display/Login Managers written in Rust that works on most GNU/Linux and BSD distributions. It can work both with or without SystemD.

Goal

This project creates a small, robust and yet customizable Login Manager which can serve as the front-end to your TTY, X11 or Wayland sessions. Lemurs uses Pluggable Authentication Modules (PAM) as its method of authentication.

Screenshot

Installation

Installation follows three steps.

Compile the codebase
Copy all files to correct positions
Enable init process to run lemurs

Arch Linux

Lemurs can be installed from the extra repository.

sudo pacman -S lemurs

# Not needed if you don't have a window manager yet
sudo systemctl disable display-manager.service

sudo systemctl enable lemurs.service

Alternatively, lemurs-git is available in the AUR.

Compiling from source

The install.sh script can be used to compile and setup the display manager on your Unix machine. This will perform multiple steps:

Build the project in release mode (requires Rust's cargo)
Setup the /etc/lemurs folder which contains some of the configuration and necessary files such as your selection of window managers.
Disables the previous Display Manager
Copies over the systemd service and enables it.

Although you might first want to set up some window managers (see Usage), upon rebooting you should now see Lemurs.

Usage

After installation you can add your environments by creating runnable scripts.

For your Xorg put your xinitrc scripts in the /etc/lemurs/wms directory. For Wayland, put a script that starts your compositor in the /etc/lemurs/wayland directory. For both cases, the name of the runnable script file is the name that is shown in the environment switcher within lemurs. Multiple Xorg and Wayland environments can exist at the same time.

Example 1: BSPWM

For the bspwm window manager, you might add the script /etc/lemurs/wms/bspwm.

#! /bin/sh
sxhkd &
exec bspwm

Remember to make this script runnable. This is done with the sudo chmod 755 /etc/lemurs/wms/bspwm command.

Upon rebooting your new bspwm should show up within Lemurs.

Example 2: Sway

For the sway compositor and window manager, you might add the script /etc/lemurs/wayland/sway. Ensure that you have sway installed and added yourself to the seat group.

#! /bin/sh
exec sway

Remember to make this script runnable. This is done with the sudo chmod 755 /etc/lemurs/wayland/sway command.

Upon rebooting your new sway should show up within Lemurs.

Configuration

Configuration is done through a TOML file. By default, Lemurs searches for a /etc/lemurs/config.toml file, but an alternative location can be specified using the --config <path/to/config.toml> flag. The configuration type can contain any subset of the available options. All the options and explanations as to what they do can be found in the extra/config.toml file. This file also serves as the default configuration.

Additionally, there is the possibility of variables in the configuration file. By default, Lemurs searches for a /etc/lemurs/variables.toml file, but an alternative location can be specified using the --variables <path/to/variables.toml. The variables.toml file may contain key-value pairs which can be referenced from within the main config.toml file.

Below shows an example of how the variables.toml and config.toml file interact.

# variables.toml
replacement_char = "+"
show_pw_title = true
password_title = "Password :)"
title_color = "white"

# config.toml
[password_field]
content_replacement_character = "$replacement_char"

[password_field.style]
show_title = "$show_pw_title"
title = "Wow a $password_title"
title_color = "$title_color"

This will be interpreted as:

[password_field]
content_replacement_character = "+"

[password_field.style]
show_title = true
title = "Wow a Password :)"
title_color = "white"

Preview & Debugging

Lemurs logs a lot of information of it running to a logging file. There are 3 log files.

/var/log/lemurs.log: This is the main log file that contains information about the control flow and is the first place you should look.
/var/log/lemurs.client.log: This is the stdout and stderr of your environment. This can help you debug your scripts in the /etc/lemurs/wms or /etc/lemurs/wayland folder.
/var/log/lemurs.xorg.log: This is the stdout and stderr of the X server. This is only used when you run a X11 based environment.

You can disable logging with the --no-log flag. This flag can be adding into your service manager script if you want to disable logging globally.

If you want to test the UI generated by your configuration file you can also run lemurs --preview. This will run a preview instance of your configuration. This will automatically create a lemurs.log in the working directory.

File Structure

Below is overview of the source files in this project and a short description of each of them and their use. This can be used by people who want to contribute or want to tweak details for their own installation.

|- src: Rust Source Code
|  |- main.rs
|  |- chvt.rs: UNIX calls to change of TTY
|  |- cli.rs: CLI argument parsing
|  |- config.rs: Configuration file format and options
|  |- env_container.rs: Handles resetting and resetting the environment variables
|  |- info_caching.rs: Handling cached username and session environment
|  |- auth: Interaction with PAM modules and UTMPX
|  |  |- mod.rs
|  |  |- pam.rs
|  |  |- utmpx.rs
|  |- post_login: All logic after authentication
|  |  |- mod.rs
|  |  |- env_variables.rs: General environment variables settings
|  |  |- x.rs: Logic concerning Xorg
|  |- ui: TUI code
|  |  |- mod.rs: UI calling logic, separated over 2 threads
|  |  |- chunks.rs: Division of the TUI screen
|  |  |- input_field.rs: TUI input field used for username and password
|  |  |- power_menu.rs: Shutdown and Reboot options UI
|  |  |- status_message.rs: UI for error and information messages
|  |  |- switcher.rs: UI for environment switcher
|- extra: Configuration and extra files needed
|  |- config.toml: The default configuration file
|  |- xsetup.sh: Script used to setup a Xorg session
|  |- lemurs.service: The systemd service used to start at boot
|  |- lemurs.pam: PAM service configuration

Shell Keybindings

Lemurs has support for some basic shell keybindings.

Ctrl + A: Go to the beginning of the focused input field
Ctrl + E: Go to the end of the focused input field
Ctrl + L: Clear the focused input field
Ctrl + U: Clear input field text before the cursor
Ctrl + K: Clear input field text after the cursor
Ctrl + D: Same as Delete
Ctrl + H: Same as Backspace
Ctrl + B: Same as Left
Ctrl + F: Same as Right
Ctrl + P: Same as Up
Ctrl + N: Same as Down

Platforms

Tested on

ArchLinux (Vanilla, ArcoLinux)
VoidLinux
Ubuntu (make sure to install build-essential and libpam-dev)
OpenSUSE (make sure to install pam and pam-devel)

MSRV Policy

Lemurs has a Minimum Supported Rust Version policy of N - 2. This means that we only use Rust languages features that have been in Rust as of 2 releases.

License

The icon used at the top of the repository is not a logo and taken as an icon from the SVGRepo. It is marked under CC0 and therefore freely distributable and amendable under a new license.

The project is made available under the MIT and APACHE license. See the LICENSE-MIT and LICENSE-APACHE files, respectively, for more information.

Contributions

Please report any bugs and possible improvements as an issue within this repository. Pull requests are also welcome.

coastalwhite / lemurs