I'm okay with the terminal, but I'm trying to learn how to use the gnome gui. The following command works no problem in the terminal: /usr/bin/java -Xms2048M -Xmx4096M -jar /home/luke/.minecraft/PixelMonServer/forge-1.12.2-14.23.5.2768-universal.jar nogui
I have created a .desktop file for it and placed it in '~/Desktop' and '~/.local/share/applications'. It looks good in both places (icon displays, I can find it in Activities) but it doesn't seem to actually do anything. Nothing fires up, and 'ps -ef | grep java' shows no running java processes.
The contents of my .desktop file are below:
[Desktop Entry] Name=Pixelmon Server Comment=Start Pixelmon Server Exec=/usr/bin/java -Xms2048M -Xmx4096M -jar /home/luke/.minecraft/PixelMonServer/forge-1.12.2-14.23.5.2768-universal.jar nogui Icon=/home/luke/Pictures/pixelmon.png Terminal=True Type=Application Categories=Game;
edit: I figured this out. If anyone else has a similar problem, check below.