First of all, apologies for reporting this here. But, there doesn't appear to be an issue tracker for Steam on non-Linux platforms.

Your system information

• Steam client version (build number or date): 2018-06-08 15:29:17
• Distribution (e.g. Ubuntu): OSX 10.13.5
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

The Linux Steam client supports setting environment variables with launch options like:

EXAMPLE=1 %COMMAND%

However, it doesn't appear to be possible to set environment variables with the OSX Steam Client.

I'm trying to use DYLD_INSERT_LIBRARIES (similar to Linux's LD_PRELOAD) in order load a dylib I wrote, to fix games with buggy input handling. Several games are unplayable with non-QWERTY keyboards, and my library rewrites the return values from SDL input handling routines, so that the games get a QWERTY keysym (that they expect).

I compiled my library, then attempted to set launch options on the game (in this case, Prison Architect): DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES=/usr/local/lib/sdl2-hooks.dylib %COMMAND%.

This is also possible with any other arbitrary environment variable, and you don't need to build my library to trigger the error. For example, launch options EXAMPLE=1 %COMMAND% also fails to execute with the same errors.

I tested this with Cities Skylines, Prison Architect and Shenzhen IO.

%command% (in lower case) also doesn't work. Not specifying %COMMAND% at all simply causes Steam to pass the launch options as a command line argument.

Actual behaviour:

When running the game, Steam fails to launch with:

An error occurred while updating {GAME} (unknown error)

(Yes, it says "updating"...)

Steam's stdout shows:

GameAction [AppID 233450, ActionID 1] : LaunchApp waiting for user response to CreatingProcess ""
GameAction [AppID 233450, ActionID 1] : LaunchApp continues with user response "CreatingProcess"
Opted-in Controller Mask: 30
Couldn't make FSRef from path: DYLD_FORCE_FLAT_NAMESPACE=1
GameAction [AppID 233450, ActionID 1] : LaunchApp failed with AppError_1 with ""
GameAction [AppID 233450, ActionID 1] : LaunchApp changed task to Failed with ""

When %COMMAND% is used, Steam on OSX appears to interpret the first environment variable as a path to the executable.

Expected behaviour:

I expect Steam on OSX to set the environment variables specified in the launch options in the same way that Steam on Linux supports.

Workaround:

1. Write a shell script into the game's Example.app/Contents/MacOS which sets the environment variables, eg:

#!/bin/bash
cd "${0%/*}"
EXAMPLE_ENV=1 ./Example "$@"

1. Point Example.app/Contents/Info.plist -> CFBundleExecutable to the shell script.

2. Run /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -v -f ${HOME}/Library/Application\ Support/Steam/steamapps/common/Example/Example.app

However, a game update may revert the changes.

Other notes:

I think this is a different issue to https://github.com/ValveSoftware/steam-for-linux/issues/4544, as that looks like the root cause was a compatibility issue with some GPU drivers. In this issue, Steam explicitly shows an error message that it was unable to start the game.

SDL, used by many games on Steam, also allows control over some of its options through environment variables, even on non-Linux platforms. Being able to set them may be useful for some users.

Steam also doesn't appear to honour the LSEnvironment property in Info.plist.