Q: Can you run a server through terminal on an OS X Server?

OS X Server is simply an application that you can install on any Mac and turn it into a server.

You can run other process on the machine (Mail, Safari, Minecraft Server... whatever) while the OS X Server application is running.

Not necessarily. Assuming this is Mac OS X Server version 10.5 the OS X Server is a separate release than the standard Mac OS X. It wasn't until later that they retired Mac OS X Server and made Server a separate app that runs on any Mac OS X install.

However, the poster may have posted in the wrong forum and mean the current version of OS X, since they mentioned the App Store.

The Short Answer:

Running OS X Server will not cause any problems running other server software, like Minecraft. This software can be controlled remotely with an SSD connection. You'll just want to verify that you enable Remote Login and your Mac's firewall allows incoming connections on port 22 (for SSH) and whatever ports your other software needs.

Long Answer:

Are you running OS X Server 10.5? That's an older release of OS X Server, released about 10 years ago. If it is, then you'll likely run into some compatibility issues, especially if it's a PowerPC Mac.

Since you mentioned the App Store you may have just posted in the wrong forum. In that case, you can indeed run any software you want remotely or heedless (only using the terminal) and remote in with SSH.

You don't necessarily need the OS X Server app from the App Store. You can enable SSH Remote Login and remote into the Mac without any server software. You can also run the server software for other software, like Minecraft, without the OS X Server software. This can be enabled in Preferences -> Sharing -> Enable "Remote Login." Just make sure you do the necessary port forwarding in your router if you want to access your programs and be able to login on the internet. If you have the firewall on your Mac installed then you'll want to add entries for SSH and any server software's ports.

If you do install the OS X Server software then there shouldn't be any problems accessing your installed server software (like Minecraft). You'll just want to check to make sure there aren't any firewall or security settings that may block the incoming ports. If there are issues getting to your server, add the ports to your firewall.

As far as accessing the OS X Server's software remotely, it's easiest to control them using VNC or Apple RDP where you have a  graphical interface. OS X Server generally has been less friendly to command-line-only administration. Being UNIX however, you could always install your own more command-line friendly server software and use that instead.

Good Luck.

The Short Answer:

Running OS X Server will not cause any problems running other server software, like Minecraft. This software can be controlled remotely with an SSD connection. You'll just want to verify that you enable Remote Login and your Mac's firewall allows incoming connections on port 22 (for SSH) and whatever ports your other software needs.

Long Answer:

Are you running OS X Server 10.5? That's an older release of OS X Server, released about 10 years ago. If it is, then you'll likely run into some compatibility issues, especially if it's a PowerPC Mac.

Since you mentioned the App Store you may have just posted in the wrong forum. In that case, you can indeed run any software you want remotely or heedless (only using the terminal) and remote in with SSH.

You don't necessarily need the OS X Server app from the App Store. You can enable SSH Remote Login and remote into the Mac without any server software. You can also run the server software for other software, like Minecraft, without the OS X Server software. This can be enabled in Preferences -> Sharing -> Enable "Remote Login." Just make sure you do the necessary port forwarding in your router if you want to access your programs and be able to login on the internet. If you have the firewall on your Mac installed then you'll want to add entries for SSH and any server software's ports.

If you do install the OS X Server software then there shouldn't be any problems accessing your installed server software (like Minecraft). You'll just want to check to make sure there aren't any firewall or security settings that may block the incoming ports. If there are issues getting to your server, add the ports to your firewall.

As far as accessing the OS X Server's software remotely, it's easiest to control them using VNC or Apple RDP where you have a  graphical interface. OS X Server generally has been less friendly to command-line-only administration. Being UNIX however, you could always install your own more command-line friendly server software and use that instead.

Good Luck.