Fixing mach_kernel file visibility using Casper

Following the release of Security Update 2015-002, it became apparent that the usually-hidden /mach_kernel file was now visible via the Finder. The mach_kernel file file is important to OS X and is stored on the root level of the hard drive on most versions of OS X (OS X 10.10.x has moved the mach_kernel file out of the root level of the Mac’s boot drive.)

To help fix this issue, Apple has made a KBase article available showing how to re-hide the /mach_kernel file using the chflags command.

As part of a post describing the problem, Tim Sutton has written a script to identify and fix the issue by using the ls command to check for the hidden attribute and then using the chflags command to re-hide the /mach_kernel file as needed. I’ve adapted Tim’s script for use in my own shop to have Casper find and fix this issue. For more details, see below the jump.