User profile for user: Korby
Korby Author
User level: Level 1
8 points

Terminal command to refresh USB peripheral device

I'm running OS 10.7.5, and I have a recurring problem with the USB ports on my Mac mini. After several days of up-time, one or more of the ports will sometimes become non-responsive. This seems to be software related, because logging off and logging back into the machine always fixes the problem (as does a restart and a cold-reboot). I was thinking maybe the "checklist" of device filenames somehow gets corrupted over time, and needs to be recreated.


Does anyone know how to refresh the list of peripheral devices without restarting, rebooting, or logging off? Ideally a terminal command? I'm hoping not to have to keep shutting down the session each time this happens to get my list of connected devices back.


Thanks very much for your suggestions for the newbie.

Mac mini, Mac OS X (10.7.5)

Posted on Jul 25, 2014 9:39 AM

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User profile for user: Brett L
Brett L
User level: Community Specialist

Jul 27, 2014 2:38 PM in response to Korby

Hi Korby,


If you are having difficulties with USB devices such as you describe, I would suggest resetting your Mac mini’s parameter RAM, as described in this article -


About NVRAM and PRAM

http://support.apple.com/kb/HT1379


Specifically -

Resetting NVRAM / PRAM

  1. Shut down your Mac.
  2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
  3. Turn on the computer.
  4. Press and hold the Command-Option-P-R keys before the gray screen appears.
  5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
  6. Release the keys.

Thanks for using Apple Support Communities.


Best,


Brett L

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User profile for user: Korby
Korby Author
User level: Level 1
8 points

Jul 31, 2014 10:21 AM in response to Brett L

Brett L,


Thanks for your suggestion, and for the links to the knowledge base articles. It was a good suggestion, and I was hoping it would solve my issue. I reset my NVRAM / PRAM and waited a few days. Unfortunately, I still have the same problem. I don't think there's a "fix" per se. I have an older Mac that runs OS 10.6, and never had this problem. This might best be served with a quick refresh of the ports when the operating system seems to lose touch with them. If not, I'll just have to keep logging off, logging in.


Thanks again for the help.


Korby

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Terminal command to refresh USB peripheral device

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