Using sudo without password on Linux to start kanata, and only kanata

[idoric]

1. Run sudo visudo -f /etc/sudoers.d/kanata
2. Adapt YourLogingUser ALL=(ALL) NOPASSWD: /path/to/kanata to your needs and save this single line

Now sudo /path/to/kanata --cfg ~/path/to/config.kbd will be executed without ever asking for a password.

3. So it's possible to automatically launch Kanata by adding the following line at the end of your ~/.bashrc file: sudo /path/to/kanata --cfg ~/path/to/config.kbd >/dev/null &.
   Important warning: I strongly advise you to first create a backup account with administrator rights, and if you use this feature, to deactivate automatic connection to your account at startup. Also, if you forget the & at the end of the line, your session will be stuck without ever finishing starting, in which case remember that it's possible to exit Kanata with lctl+spc+esc.

I needed to start Kanata at user level (shared computer), but without giving my user account access to the /dev/input/* files (you have the right to think I'm paranoid). I can't get both simultaneously with systemd (#130), and creating a special account to run Kanata would still require the trick above (the technique of assigning a wrong shell and then using su --shell is no longer functional by default precisely for security reasons). And ultimately this is the simplest solution I found.

This solution is satisfactory for me, but it would be possible to do better:

• create a special "kanata" account as described in https://github.com/jtroo/kanata/wiki/Avoid-using-sudo-on-Linux, and adapt the /etc/sudoers.d/kanata and ~/.bashrc files as follows: YourLogingUser ALL=(kanata) NOPASSWD: /path/to/kanata and sudo -u kanata /path/to/kanata --cfg ~/path/to/config.kbd >/dev/null &. (You can even lock that account with the command usermod -L kanata)
• I haven't tested what would happen if I logged in twice simultaneously (e.g. locally and via ssh).