I am not a Linux pro nor a Java pro, but I am setting up a Minecraft server on Ubuntu 16.04. System has 8GB RAM.

I followed all the directions for setting up the server (which is very simple) but when I ran the command:

sudo java –Xms1024M -Xmx1024M -jar minecraft_server.1.9.2.jar nogui

I got this:

Error: Could not find or load main class –Xms1024M

I then simply ran (after about 1 hour of hacking around trying to install different JREs): sudo java -jar minecraft_server.1.9.2.jar nogui and it worked.

What is the difference and what are the possible issues by not specifying RAM?

Additionally, what is a good practice for starting up the Minecraft server via SSH and letting it run in the background after disconnecting?

Edit:

When running java -jar minecraft_server.1.9.2.jar nogui I am seeing this output:

2016-05-08 14:30:35,683 ERROR Cannot access RandomAccessFile {}) java.io.FileNotFoundException: logs/latest.log (Permission denied)
2016-05-08 14:30:35,684 ERROR Unable to invoke method createAppender in class org.apache.logging.log4j.core.appender.RollingRandomAccessFileAppender for element RollingRandomAccessFile java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)

Followed by an endless list of these:

at kx.a(SourceFile:44) [minecraft_server.1.9.2.jar:?]
at kx.b(SourceFile:54) [minecraft_server.1.9.2.jar:?]
at kx.a(SourceFile:44) [minecraft_server.1.9.2.jar:?]
at kx.b(SourceFile:54) [minecraft_server.1.9.2.jar:?]
at kx.a(SourceFile:44) [minecraft_server.1.9.2.jar:?]
at kx.b(SourceFile:54) [minecraft_server.1.9.2.jar:?]
at kx.a(SourceFile:44) [minecraft_server.1.9.2.jar:?]
at kx.b(SourceFile:54) [minecraft_server.1.9.2.jar:?]
at kx.a(SourceFile:44) [minecraft_server.1.9.2.jar:?]
at kx.b(SourceFile:54) [minecraft_server.1.9.2.jar:?]