Mac OS X monitor messages during boot

Contributed by macster September 30, 2004  
Tagged: Mac system administration

The graphical booting process is pretty, but there are times we want to see what is happening to the system while it boots. This can be particularly beneficial when troubleshooting problems.

To view the boot messages for the current boot only (and return to the graphical display on the next boot), press command-V while the system is booting. The command key is the key with the apple and looping squiggly symbols typically next to the spacebar.

To make this change to the system permanent, you must make a simple firmware setting change. This is easily done using the nvram command and the sudo authentication system from a terminal window:

sudo nvram boot-args="-v"

To turn off this feature, use:

sudo nvram boot-args=

The nvram sets and queries the firmware settings. To display all of the settings and their current values, use:

sudo nvram -p