local shared steam installation library

fair warning: ive not been able to test this yet, i will be able to do so sometimes this summer :3

if you try this, please tell me if it didnt work

on windows steam installs games in a shared folder in programfiles/data, this does not happen, since steam on linux runs entierly inside your own user folder. this is good design, however its kinda bad when 2 users on the same linux machine wants to download the same large game

on linux the short solution is creating a folder owned by a special group, for example a group called steam, then both users sets itself inside of steam settings

the issue then is permissions. if one user creates a folder, the other may not be able to use it.

so i tried my best to make a nixos config that sets up the folders and permissions to make sure one user does not lock out the other user from editing the installs

the config uses a separate steam user, to simplify the creation of the folder and group, totally uneccecary, you could do this yourself…

{ pkgs, ... }:

{
  # Group to give to users to access shared storage
  users.groups."steam" = {};

  # User to own the folder, and automatically create it
  users.users."steam" = {
    description = "Steam Shared Library User";
    group = "steam";
    home = "/home/steam/";
    createHome = true;
    homeMode = "770"; # Group may read/write and execute
    isSystemUser = true;
  };
}

then we also manually have to set some flags to force new files and folders to inherit permissions

# Run this inside /home/steam

# See flags
getfacl .

# Set the setgid (aka use parent group)
chmod g+s .

# Set default permissions
setfacl -d -m g::rwx
setfacl -d -m o::0