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Linux Setup Guide

SteaMidra runs natively on Linux but the architecture differs from Windows. This page covers everything specific to the Linux build.

TL;DR

  • LumaCore is Windows-only. It is a Steam-client DLL hijack via dwmapi.dll. There is no Linux equivalent shipping today.
  • On Linux SteaMidra uses SLSsteam for license/family-share injection and SLScheevo for achievements. Both run as a LD_AUDIT-style injection into the Steam process.
  • Manifests, depot keys, ACF writing, depot decryption, and the rest of the SteaMidra pipeline work the same as Windows.
  • The Auto LC Setup button is hidden on Linux. Use Quick Tools → Set up Linux tools (SLSsteam + .NET 9) instead.

What works on Linux

Feature Status Notes
Add game (Lua + manifests + depot keys + ACF) Works Same code path as Windows.
Download via DepotDownloaderMod Works Needs .NET 9 on PATH. SteaMidra installs it via the Linux setup tool if missing.
Download via Steam-native fetcher Limited Steam needs SLSsteam injected at startup so it accepts the app id. Uninjected Steam shows "Purchase".
Achievements Works (SLScheevo) Different from LumaCore but produces the same end result.
Family bypass Works (SLSsteam) The injection is what bypasses the in-family check. Re-inject after every Steam update.
Workshop downloads Works steamcmd Linux binary is bundled in third_party/.
Cloud save scan / restore Works rclone Linux binary picked automatically.
Manifest preserver Works Inotify-based watch on Linux, ReadDirectoryChangesW on Windows.
LC Online Fix toggle Hidden Windows-only; the button does not render on Linux.
Auto LC Setup Hidden Windows-only; replaced by the Linux setup tool.
HyperVisor (HVAuto) Hidden Windows-only; Linux has no equivalent code path.
Context Menu (Explorer) Hidden Windows-only.

Supported distros

Tested on:

  • CachyOS (latest, kernel 6.13+)
  • Arch Linux (rolling)
  • Debian 12 / 13, Ubuntu 24.04, Fedora 41
  • Steam Deck in Desktop Mode (SteamOS 3.6+)

Other distros usually work if Steam itself runs there. The path detector probes ~/.steam/root, ~/.steam/steam, ~/.local/share/Steam, the Flatpak sandbox at ~/.var/app/com.valvesoftware.Steam/data/Steam, and the Snap install in that order.

Step-by-step

1. Get SteaMidra

Two options:

  • AppImage (SteaMidra-x.x.x-linux.AppImage): chmod +x, double-click. Easiest path.
  • ZIP (SteaMidra-x.x.x-linux.zip): extract, run ./SteaMidra_GUI.

Both bundle Python and the GUI runtime. No system Python needed.

2. Install SLSsteam + SLScheevo

Open SteaMidra, go to Quick Tools, click Set up Linux tools (SLSsteam + .NET 9).

What this does:

  1. Detects the Steam install path.
  2. Downloads the latest SLSsteam release from GitHub.
  3. Drops SLSteam.so and library-inject.so into the Steam folder.
  4. Verifies .NET 9 is installed; offers to fetch the Microsoft installer if missing.
  5. Optionally writes a desktop shortcut that launches Steam with the injection.

If you already have .NET 9 somewhere unusual (e.g. ~/.dotnet/dotnet), SteaMidra picks it up via the user dotnet config or the standard ~/.dotnet path.

3. Restart Steam from SteaMidra

This is the step Linux users miss most often. SLSsteam injects via LD_AUDIT at startup, so a Steam process started outside SteaMidra is not injected and ownership/family-bypass will not work.

Use the Restart Steam button on the Home tab (or Quick Tools → Kill Steam → Start Steam). The status line confirms the injection:

Steam process killed (PID 678253).
SLSteam libraries found at /home/you/.steam/steam/SLSteam.so + library-inject.so.
Starting Steam with SLSteam injection.
Steam started (with SLSteam).

If it instead shows:

SLSteam libraries not found: SLSteam.so, library-inject.so
Starting Steam without SLSteam injection.
Steam started (without SLSteam).

…the install step has not run yet. Go back to Quick Tools.

4. Add a game

Same as Windows. The Home tab walks you through it. After the depots download, the game shows up in Steam (no restart needed; SLSsteam picks up new lua files dynamically).

Troubleshooting

"Steam installation path couldn't be found"

The path detector covers the standard locations. If yours is non-standard:

  • Set the path manually in Settings → Steam path.
  • Or symlink ~/.steam/root → /your/steam/install.

Games show "Purchase" instead of "Install"

Steam was started without SLSsteam injected. Use the SteaMidra Restart Steam button to relaunch with injection.

SLSteam libraries not found

The setup tool has not run, or the SLSsteam files were wiped by a Steam update. Re-run Quick Tools → Set up Linux tools.

If you manually placed SLSteam.so and library-inject.so under the Steam folder, current builds check that location after the managed install path. Use Restart Steam again after placing the files.

SLSsteam extraction fails on CachyOS or Arch

Current builds extract the SLSsteam archive with Python first, then fall back to 7zz, 7z, or 7za using a cleaned subprocess environment. If you still see a readline or shell symbol error, install the distro package for p7zip or 7zip, then run Set up Linux tools again.

.NET 9 errors on download

DepotDownloaderMod runs on .NET 9. If dotnet --list-runtimes does not list a 9.x entry:

  • Use the SteaMidra setup tool's .NET 9 step (it fetches the Microsoft installer for your distro).
  • Or install via your package manager: sudo pacman -S dotnet-runtime on Arch, sudo apt install dotnet-runtime-9.0 on Debian/Ubuntu.

Encountered 401 for depot manifest

DepotDownloaderMod is logging in anonymously. Some manifests (e.g. the base app id of titles like Ready or Not, app 1144200) require an authenticated account. Workaround: use the Home tab's Steam download path instead — it goes through the injected Steam client which has authentication via your account.

Family bypass not working

SLSsteam handles family bypass on Linux. If a friend in your Steam Family is playing a shared title and you see "Currently Unavailable":

  1. Confirm SLSsteam is injected (status line on Restart Steam).
  2. Confirm the game's lua is present in config/stplug-in/.
  3. Restart Steam from SteaMidra (not from a desktop icon).

Steam Deck specific

  • Run from Desktop Mode, not Game Mode. The injection cannot attach in Game Mode.
  • Steam Deck's read-only root means you cannot install .NET 9 system-wide. Use the user-local ~/.dotnet/dotnet install path; the SteaMidra setup tool defaults to this.
  • Adding STEAM_RUNTIME=0 is rarely needed but works around some Proton+SLSsteam edge cases.

Differences from Windows

Topic Windows Linux
Ownership injection LumaCore (DLL hijack via dwmapi.dll) SLSsteam (LD_AUDIT of SLSteam.so)
Achievements LumaCore (in-process protobuf rewrite) SLScheevo (separate Steam client)
Library entries LumaCore picks them up live SLSsteam picks them up live; Steam restart not needed
ACF writes Skipped (LumaCore handles ownership) Required (SLSsteam reads ACFs)
.NET 9 Optional (only for DepotDownloaderMod) Required for DepotDownloaderMod path
Auto-update In-app via the updater script In-app; AppImage variant updates via separate AppImage download

Reporting Linux bugs

When opening an issue please include:

  • Distro + version (lsb_release -a or cat /etc/os-release)
  • Steam install location (echo $HOME/.steam/steam resolves the symlink)
  • The four lines from the Restart Steam status block
  • Whether dotnet --list-runtimes shows a 9.x entry
  • The contents of the Logs panel from inside SteaMidra (last 50 lines is plenty)