Suddenly X Gives Black Screen With Small Clock Cursor

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So, I don’t know what the heck happened, but I have what looks like a solution: a number of important files in /dev somehow had their permissions changed. I had to do the following:

chmod a+rw /dev/null chmod a+rw /dev/urandom chmod a+rw /dev/zero chmod a+rw /dev/full chmod a+rw /dev/random

After which X started and the complaints about /dev/null went away. As I worked thru fixing first /dev/null, each step got me a bit further, with more complaints about inaccessable /dev/ entries, so I just kept fixing them until the complaints went away.

I also compared permissions in /dev against my Fedora 19 netbook, which is how I knew what permissions to use for the rest, as well as being where I
found correct permissions, as well as /dev/zero and /dev/full being wrong.

I have NO CLUE what hosed the permissions, and I can’t be sure that there may not be some other items also wrong (that I can’t see because they don’t appear on the F19 system).

Can anyone suggest an accurate way to have the system fix all the permissions in /dev? some arcane options on rpm, perhaps?



5 thoughts on - Suddenly X Gives Black Screen With Small Clock Cursor

  • Ah, it was too good to be true. Reboot returns those files to the incorrect permissions.

    Suggestions on where to look will be welcomed.

  • Nothing I can see in the logs looks particularly damning.

    running that right now, will post again if anything interesting turns up.

    I was thinking of that, but the amount I know aobut udev wouldn’t cover the head of a pin. Open to suggestions, though.

  • Looking in /lib/udev/rules.d/50-udev-default.rules I see:

    KERNEL==”ptmx”, GROUP=”tty”, MODE=”0666″
    KERNEL==”null|zero|full|random|urandom”, MODE=”0666″

    so if I understand them right, /dev/ptmx, /dev/null, /dev/zero, /dev/full,
    /dev/random, and /dev/urandom should all come up as ‘rw’ for all users after a system boot, but they don’t. I reboot and they all come up as
    0644, crw-rw—-. grepping for “null” in /lib/udev finds only that single entry in all of the files, as does “ptmx”.

    So, I wonder if something is preventing this file from being run (which seems unlikely, given that it contains a ton of rules which would all be skipped). I note that /etc/udev/rules.d contains a rules file with exactly the same name (which sets up some firewire stuff) and wonder if that’s a problem,… anyone know?

  • sigh. the problem, had this been a car, could have been diagnosed as:
    “There’s a loose nut behind the wheel.” I.e., me. it’s exactly due to the duplicate udev rules filenames, one in /etc/udev/rules.d and the other in lib/udev/rules.d. Self-inflicted damage. PROBLEM SOLVED.