I don't think this is the best long-term solution. This PR just masks the locale problem; anyone who installs a pre-built linux artifact on a system with a comma decimal locale will still encounter this issue because the locale change here is system specific/dependent and isn't fixing the root cause.

That is true, mainly wanted to get attention to this issue, as it essentially makes you unable to load motions onto the model in the GUI. I do not know how to fix the issue at its root cause.

There are a few problems with this change:

1. Installing opensim should not override the system locale settings to en_US.UTF-8. This would create a very unexpected problem for everyone who does not use en_US.UTF-8 (ex. people who are not in the United States).
2. Executing arbitrary Sudo system configuration specific commands in a build script should be avoided. If it can't the user should be well aware of what it is doing.

Then I believe this pull request can be closed? Though the issue #3924 will still remain. I might take a look to see if i could fix it, but I believe someone more experienced is more likely to find the root cause of this. I already closed the PR for the opensim-gui now, because the root cause lies in opensim-core.

Agreed that build scripts shouldn't make global changes to either Locale or Path in order to avoid unintended side-effects, so closing the PR but thanks for bringing the issue to the forefront @ksomml and for the feedback @alexbeattie42 and @halleysfifthinc