Minecraft jar not marked as executable

Solution 1:

The important part is in your message:

"The file '/home/mike/Downloads/minecraft.jar' is not marked as executable. If this was downloaded or copied from an untrusted source, it may be dangerous to run. For more details, read about the executable bit."

Command line

The command:

sudo chmod +x /home/mike/Downloads/minecraft.jar

will make it executable. Be sure to read the 2nd part of the message: make sure you got it from a trusted source.

GUI

If it is easier for you, you can also view the file with Nautilus and richt click it, open Properties, open the Permissions tab, and tick the box that says:

Execute: Allow executing file as a program.

Other

From a very reliable source I have been told you can also do:

java -jar /home/mike/Downloads/minecraft.jar