Are the pre and post launch script env vars available inside the launched instance?

[mainrs]

Id like to know what instance a user launched inside my mod. Is that possible somehow?

I thought this might be more reliable than checking the absolute path of a class inside my mod jar. And then seducing it's location based on the returned file path.

[TheKodeToad]

You can use

String instanceName = System.getProperty("org.prismlauncher.instance.name");

See https://github.com/PrismLauncher/PrismLauncher/blob/develop/libraries/launcher/org/prismlauncher/SystemProperties.java to see all of the properties that are available.