Troubleshooting “Unexpected argument” error when running defaults write

HTML is not a script, it's a markup language. You need a browser to render HTML. To view it, you probably want

open sysinfo_page.html

I had a similar problem trying to run a Java-based web application server. For me, the problem turned out to be that my environment variables (in particular, JAVA_HOME) weren't being set, which is because the instance of Bash (or whichever shell you have it use) doesn't start as a login shell OR an interactive shell, so your profile script (e.g. ~/.profile, ~/.bashrc, etc.) doesn't run automatically.

For me, the solution was to add the following to my script:

source ~/.profile

The source command causes the commands in ~/.profile to be executed in the current shell; this way the environment variables being set by that script will be available to the instance of Bash that platypus starts.

Note that it's important that you don't just execute the profile file as a shell script itself; that will cause it to run in its own shell, which will exit immediately afterward; any variables it sets will cease to exist as soon as it exits. This is why we have to use the source command.

As an alternative, you can just set the necessary environment variables directly in your script.

Hope this helps!