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Booting your Mac OS X in safe mode with NVRAM modifications

Some times we might require our mac to be booted into safe mode to fix/resolve some issues. Your mac can be booted into safe mode in two ways

  1. Hold "Shift" key on your mac keyboard to boot your mac into safe mode.
  2. If you can not boot with your keyboard(in case your keyboard is not recognized or some problem)  then you can perform below operations :
    1. Establish a remote connection such as SSH to the mac.
    2. Run in terminal " sudo nvram boot-args="-x", press enter/return. ( You can also add "-x -v" for verbose mode booting of safe mode)
    3. To reset back to normal mode run "sudo nvram boot-args=" " (without any arguments).

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How to find firmware or boot ROM version in Mac OS X

Firmware and boot ROM version of your mac can be found in two ways.
Way 1 :
1. From "Apple" menu , choose "About This Mac" menu item. 2. Click " More Info " to open "System Profiler" application. 3. Under Contents -> Select Hardware Tree item.
On the right side panel Under hardware overview section, we can see Boot ROM Version and SMC (Firmware) Version.








Way 2 :
Run the below command in terminal to get boot ROM version and SMC(firmware) version :
$ system_profiler SPHardwareDataType | grep -i "Version" | awk -F ':' '{print $1 $2}'

How to disable USB ports on Mac OS X Mavericks, Yosemite or El Capitan ?

We might wonder how to disable the USB ports on Mac to prevent data copy to external USB mass storage devices. The USB kext on os x is loaded at the time of start of the system, this can be loaded / unloaded using kextload or kextunload command. To disable USB port on Mac , follow below steps:
On Macs running Mountain Lion, Mavericks  and Yosemite:
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sudo kextunload -b com.apple.driver.AppleUSBODD
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On Mac running El Capitan:
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