Booting with non-verbose mode

For some reason, my iMac was shipped with verbose booting turned on. In this mode, all boot messages that the core Unix-system within OS X creates, are displayed as the system boots up. This is of course completely harmless, but keeping with the nice look and feel of the Mac, it has annoyed med for quite some time.

I finally got around to try to figure out what the problem was. It turns out that there is a boot parameter you can use to turn this feature on or off (really just on, the absences of this parameter is the same as off). It is a parameter in nvram, which can be set or displayed with the command “nvram”. To see what the parameters are, go to the terminal, and type

   sudo nvram –p

and look for “boot-args” (or type sudo nvram –p | grep “boot-args”). In my case the boot-argswhere “-v”, for verbose.

To turn this off, just type

   sudo nvram boot-args=

and your Mac should be booting in normal mode, without displaying all these messages. If you need to see the messages again, go back to the terminal and type

   sudo nvram boot-args="-v"

and it is back to booting in verbose mode. 

If you would only like to turn on verbose mode for this one boot, you could press and hold command-v when you turn on the system, and it will boot verbose mode only this one time, reverting to normal (graphical) boot the next.

Why my iMac was shipped with the verbose mode on I do not know, but finally it is back to normal.