I just installed the 10.8.5 Supplemental updater.

Apple apparently messed up, so that now, "mach_kernel" is visible on the HD.

I suppose there is a Terminal command or such, but I know not what it is or how to do it.

What is the best way to again make this invisible?

I assume that the following works in 10.8 as well as in previous incarnations of OS X:

Rename mach-kernel by putting a period in front of the name, making it .mach-kernel

Since mach_kernel, despite not normally being visible, is not preceded by a dot in a normal installation, I'd be disinclined to fix its abnormal appearance with an abnormal renaming. A better approach would be to change its file flag via Terminal's chflags command by typing

sudo chflags hidden /mach_kernel

and hitting Return. At the password prompt, one would type one's administrator password (note that no manifestation of the password-entry keystrokes will appear) and hit Return again.

Installed on a backup drive and sudo chflags hidden /mach_kernel did the trick.
I think I will wait for Apple to release an update to their update. Surprisingly Onyx did not make it invisible.
As a side note the new iTunes still has the many many repair permissions not repairing

I must be doing something wrong. This is what I get:

Last login: Thu Oct 3 23:00:01 on ttys000
Harv:~ harvey$ sudo chflags hidden /mach_kernel

WARNING: Improper use of the sudo command could lead to data loss
or the deletion of important system files. Please double-check your
typing when using sudo. Type "man sudo" for more information.

To proceed, enter your password, or type Ctrl-C to abort.

Password:
Sorry, try again.
Password:

I am certain my password is correct and the Shift key is disabled (as normal).

Any suggestions?

P.S. I just discovered that MacPilot has the capability to: "Make Items Invisible".

I have not done that yet, but do you think it's worth a try?

That's consistent with an incorrectly entered password, so I don't know what to tell you. I suppose you could type your password into a text editor or a word processor to be certain that it was correct, then cut & paste it into the Terminal window. I tried that and it worked as expected. This would rule out the possibility that you were somehow entering something other than what you thought you were.

Of course, you'd then want to replace your hard drive before the NSA could extract your password from the residual bits...

Arrrgh! I just tried the copy & paste trick to no avail. I have used Terminal in the past and of course had to enter my PW, always without issue.

Might there be a place in Keychain I can verify my Admin PW?

Indeed I am confused and am now concerned that my Admin PW no longer works.

So I went to System Preferences/Users & Groups, and then was successful in unlocking my Admin account, so that indicates (to me) that what I believe to be my PW is just that and that I can enter it ok. I can also unlock my Keychain (same PW)

Have you other suggestions?

The Saga…

1. I booted in to the volume with the Supplemental on it to ascertain if my password would work as as I presumed.
2. I then concluded (perhaps foolishly) that something must be interfering/conflicting when I entered my PW in Terminal.
3. So I rebooted in Safe Boot and then tried to execute the commands as suggested. And voilà. The file is again hidden. Good news me thinks, indeed a very clever chap that Harvey guy…
4. But speaketh not too fast. When I attempted to boot out of Safe Mode, I discovered the volume was no longer bootable. The "mach_kernel" was not made invisible, it was deleted!
5. My vocabulary was then exercised to its full…
6. I have now replaced the "bad" volume with a known (pre-Supplemental) volume and all is again, right with the world. At least for now.
7. Perhaps I had a corrupted download--I really haven't a clue, only guessing. For sure I'm confused. Not since 1984 have I had such grief with an updater.

By the time I recover from this mish-mash, Mavericks will be released; and I am certain to give it go. In any event, the new OS will again be on an external backup.

Wow! Sure glad you had a good backup.

How exactly did you determine that mach_kernel had been deleted?

The new combo update works fine for me and includes the supplemental. It was only the Supplemental Update by itself that caused me any problems on my backup disk. Good Luck

A well asked question. Alas, I did not truly determine that the mach_kernel had been deleted, only presumed such as the volume was no longer bootable (ad nauseam grey screen, no spinning, no logo, nada).

Now that you ask, I should have done a search from a different/bootable volume. But the cursed volume has now been SuperDupered with a good/valid 10.8.5, so no value in searching that.

Doing a search (as you allude) may have proven interesting, very interesting. And perhaps even valuable. With I hadda thought of that…

Mark, I did use the Combo updater. Is your mach_kernel visible?

I can't believe Apple would allow such a potentially harmful condition to persist.

As so many folks fussed about that condition, I wonder if Apple published a silent updater. (My update was within 10 minutes of release. Perhaps I jumped the gun…)

Now that I know what to expect, I may try a fresh download--especially if the Supplemental has been supplemented.

Suggestions, thoughts, & musings always welcome (and appreciated).

In light of Mark's post, I decided to again DL the Supplemental/Combo updater and install it on a backup volume. Voilà! And joy throughout the kingdom. No visible mach_kernel.

Still, I'll test it more throughly before installing it on my primary drive.

I thought the same thing, but an update I did the morning of 10/05/2013 still produced a visible mach_kernel.

Perhaps someone could comment on the "danger" of having this file visible, absent it being deleted.

I wish I knew what to say, Ira. I did the combo update a few hours ago and all is dandy. I believe I got the 10.8.5 (Supplemental) Combo updater Here.

If your update came from elsewhere, perhaps this link is worth a go.

Sorry my help is not so much…

The original download was through Software update on a backup drive and had the mach_kernel displayed. I then followed dkmarsh's terminal instructions (
sudo chflags hidden /mach_kernel) and it hid the file. I had no problems with that drive. I then tried the new combo updater from10/3 OS X Mountain Lion Update v10.8.5 (Combo) and had no problems with that installations or on another backup drive and they installed without the mach_kernel being visible. So I finally got up the nerve to install on the main drive with the new combo and no problem either as that was hidden also .So far so good on all drives

The primary purpose of making files invisible in OS X is to protect them from being inadvertently damaged by the uninformed user. The school of file management. Apple keeps them them out of harms way by keeping them out of site. I have known a few users who habitually run with invisibility turned off and their systems work perfectly well. I tried running that way for an hour or so several years ago, but the folders were so cluttered with normally invisible files I found I really did not like it and quickly switched back. These days if I want to find an invisible file or folder for any reason, I use the "Go" menu in Finder or turn on the "File invisible" attribute in a Finder Search window.

it's also to stop them from outright screwing things up.

I've almost lost count of the number of users that have dug around in their iphoto or iTunes library files and decided to start organizing it. (or simply started renaming folders or tracks) "Why are my pictures all there (thumbnails) but when I click on them it shows a big question mark?"

They package it now. But hiding ~/Library, THAT I find a continuous nuisance.