Error on executing steam proton app via command-line

Solution 1:

Proton/SteamPlay's wine is located in ~/.local/share/Steam/steamapps/common/Proton*

Your game's wineprefix is located in ~/.local/share/Steam/steamapps/compatdata/$appid/pfx, you can find the $appid in ~/.local/share/Steam/steamapps/common/$your-game/steam_appid.txt (to use it, set the WINEPREFIX environment variable to that path)

Edit: Your game files are located in ~/.local/share/Steam/steamapps/common/$your-game

To run a *.exe file with Proton you can use the following commands:

Change working directory to Proton's:

cd ~/.local/share/Steam/steamapps/common/Proton*

Run the executable, for example:

STEAM_COMPAT_DATA_PATH="$HOME/.local/share/Steam/steamapps/compatdata/$appid" ./proton run dist/lib/wine/fakedlls/cmd.exe

Solution 2:

You need to create ~/.proton. It can be any directory and can be empty.

On the command-line you can use:

mkdir ~/.proton