swaywm-alttab

A tool which brings familiar Alt-Tab shortcut from stacking window managers (used in Windows, Mac, KDE, GNOME, etc.) to Sway WM workspaces on Linux

Installation

Install a binary crate with cargo:

cargo install --git https://github.com/ar7eniyan/swaywm-alttab

The swaywm-alttab binary is going to be in ~/.cargo/bin, add it to PATH if needed

TODO: make an AUR package.

Configuration

To use this program, you'll need to find the input device file for your keyboard. Input device files are placed by the Linux kernel in /dev/input/eventN. There are some tools to show the available input devices: for example sudo evtest or sudo libinput debug-events. Without using any third-party software, the names and other attributes of input devices can be found by cat /proc/bus/input/devices.

Seting up the permissions for keyboard input/output to work

In order for swaywm-alttab to properly access input devices and uinput kernel device as an unpriviliged user, the following steps should be made:

• Create udev rules for /dev/input/ and /dev/uinput:
  • /etc/udev/rules.d/72-swaywm-alttab-input.rules:

    KERNEL=="uinput", MODE="0660", TAG+="uaccess"
    SUBSYSTEM=="input", MODE="0660", TAG+="uaccess"
    

    TODO: does this put a security risk on a system?
• Make uinput kernel module to load on boot (doesn't load automatically at least on Arch):
  • /etc/modules-load.d/uinput.conf:

    uinput
    

• Reboot or run the following:

  # Reload udev rules
  sudo udevadm trigger
  sudo udevadm control --reload
  # Load uinput kernel module
  sudo modprobe uinput
  

Usage

After you found the /dev/input/eventN path for your keyboard and set up the permissions, start the tool in a terminal to check if everything works correctly. Pass the input device path as an argument, replacing N with yout actual device number:

~/.cargo/bin/swaywm-alttab /dev/input/eventN

The actual shortcut is not Alt+Tab, but (LMeta|RMeta)+Tab, following the default Sway usage of Meta key for navigation. Focus on different workspaces for the tool to start keeping track of them, and press the key combination to see if it works.

To run swaywm-alttab on sway startup, add the following line to ~/.config/sway/config:

exec ~/.cargo/bin/swaywm-alttab /dev/input/eventN

Custom shortcut

The default shortcut is (LMeta|RMeta)+Tab, remember that. But if you want, you can configure any key combination by using --modifiers and --trigger options. For example, the default setup would look like this if redundantly configured with the mentioned options: swaywm-alttab --modifiers KEY_LEFTMETA KEY_RIGHTMETA --trigger KEY_TAB <input device>. Supported key names (KEY_TAB, etc.) are listed here and are the EV_KEY keycode names from the Linux API code. The app supports setting 1 or 2 modifier keys, and exactly one trigger key if you need to change it for some reason.

To use the Alt+Tab shortcut instead of Meta+Tab (like on most platforms), run the app like this:

~/.cargo/bin/swaywm-alttab <input device> --modifiers KEY_LEFTALT

Warning: be careful when passing --modifiers option since it takes up to two values, which would mistakenly try to parse the path as a key name in this case:

~/.cargo/bin/swaywm-alttab --modifiers KEY_LEFTALT <input device>
error: invalid value '<input device>' for '--modifiers <MODIFIERS>...': no such key code

Debugging

To enable logging, set environment variable RUST_LOG to one of these values: error, warn, info, debug, trace. The default log level is info. For more complex selectors, see env_logger's documentation.

Further development

• Find a more convinient way to switch workspaces (ideally, by their con_id)
• Make a key combination configurable
• Implement input device autodetection if it's possible
• Add workspace overview UI like in sov

License: GNU GPLv3, see COPYING

Copyright (C) 2023  Arseniy Kuznetsov

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.