Thanks again for the quick reply. Unfortunately I forgot to post the results from when I attempted your suggestion earlier:
root@ubuntu:~/minecraft# java -jar '/home/user/minecraft/forge-1.7.10-10.13.0.1184-installer.jar' --installserver
Exception in thread "main" joptsimple.UnrecognizedOptionException: 'installserver' is not a recognized option
at joptsimple.OptionException.unrecognizedOption(OptionException.java:89)
at joptsimple.OptionParser.handleLongOptionToken(OptionParser.java:493)
at joptsimple.OptionParserState$2.handleArgument(OptionParserState.java:56)
at joptsimple.OptionParser.parse(OptionParser.java:433)
at cpw.mods.fml.installer.SimpleInstaller.main(SimpleInstaller.java:26)
I've been playing around with various syntaxes to try and install it, even updated my java repositories, to no avail. Can't help but feel like it's some super obvious tiny thing I'm missing. Really grateful for your time and suggestions.
Edit: Seems I was correct about the super tiny issue. For anyone else experiencing something similar, CAPITALS matter.
"--installServer" instead of "--installserver" fixed the issue.
Thanks so much for your help!