Get a flash drive from Mr. James and plug it in. Observe the name of the flash drive for later use.
Click on the magnifying glass (upper right corner of screen) for the OSX Spotlight search, or use Command-Space to open it.
Type “terminal” and hit the enter key to open a terminal window
in the terminal window type this command, substituting the name of the USB flash drive:
/volumes/flashdrivename/mcupdate.sh
For example, if the name of the flash drive as displayed on the desktop is “red”, you would type:
/volumes/red/mcupdate.sh