I host my server at pingperfect.com and i use their rcon console. My problem is when i do commands like this:
(Example) server.hostname "[INT] Unknown Server

It appears like this:
server.hostname "[INT]"

Could anyone help me?

You need to close the quotations at the end.

Nope, it doesn't work.

https://gyazo.com/228351af7866e0be1346d8d1d90d16a9

Looks like whatever you are using the send the command is removing the quotation marks when it sends it. Try:

server.hostname ""test 1""

or

server.hostname \"test 1\"

None of them work.

You may want to see out another tool to use then, as the first method with quotation marks is the normal method.