how do I find out what's hanging me up?

[John G. Heim]

If you can configure a serial console, you would be able to read those 
messages. But I still say it's a process in an uninterrruptable sleep 
which means the kernel can't kill it during a normal shutdown. That, in 
turn, implies that it is a kernel bug in a device driver. In fact, I 
will wager it's the driver for your sound card and the process that is 
in an uninterruptable sleep is pulse. That's just a guess though.
If the machine is kind of old, it is very likely to have a serial port. 
Then you need another computer and a null modem cable to configure a 
serial console.  There is a really good serial console howto on the web. 
No point in me reiterating all that. If you have never configured a 
serial console before, you are not likely to have a null modem cable 
lying around. But setting up a serial console is a valuable skill for a 
blind linux sysadmin to have. You can even do a serial console install 
of VMware ESXI.

PS: Thanks for the tip on tap tap see. I'd never heard of it before. I 
am going to try it today. When I need to have a screen read to me by my 
phone, I have been using the knfbReader app.

On 07/03/2016 01:08 PM, Mark Peveto wrote:
> I've been working on this more today, pulling out all the tools I've got.  To the point i'm using tap tap see to try and get an idea of what's on my screen when reboot hangs.  The most i can
> get  is a message about bus socket display, and a command prompt.
> Not real helpful, but I guess it's a start.
>
> Mark Peveto
> Registered Linux user number 600552
> Sent from sonar using alpine 2.20.13
>
>
> On Sat, 2 Jul 2016, Tony Baechler wrote:
>
>> On 7/2/2016 1:54 AM, Mark Peveto wrote:
>>> The short version of a long story.  I've just installed sonar on a dell pc.
>>> I've also got it installed on a compaq/hp machine, where the followig
>>> problem doesn't exist.  On the dell, sudo reboot seems to hang.  Sudo
>>> shutdown works fine.  I've tried sudo shutdown -r now, sudo systemctl
>>> reboot, and
>>> other options.  How, without sighted help, can I find out what's causing
>>> this machine to hang when I reboot.  What's strange is this...why does it
>>> shut
>>> down just fine, but not reboot?
>> I'm not familiar with Sonar, so consider these random guesses. First, have you
>> looked in /var/log/syslog and kern.log? There might be a process not shutting
>> down properly. If you halt the system, all processes are killed and all
>> filesystems are unmounted. A reboot only resets the system, so I suppose it's
>> possible that a process is behaving badly or the kernel can't unmount a
>> filesystem. I see this sometimes with slow USB devices, like if I copy a ton
>> of files to my SD card. A more likely explanation is an ACPI or power
>> management issue. You didn't say how old the machines are, but it could be a
>> BIOS bug. Recent kernels should work around this. Without knowing the age of
>> the machine and the kernel version, I can only guess.
>>
>> Also, the machine isn't a laptop, right? Laptops usually have power management
>> issues. On Debian, there is a package called acpi-tools. Try installing it if
>> it isn't there or purging it if it's there. I have better luck without it
>> installed. I would bet syslog and kern.log would have clues to your problem. I
>> would check those first. Make note of the time you reboot the machine and look
>> at those files with less. You could try booting a live CD to avoid adding all
>> of the boot messages to the logs. You didn't say if that happens on a live CD,
>> booting from the hard drive, other distros, etc. I''ve noticed most live CDs
>> have strange shutdown problems. You might have to pass a parameter on the
>> kernel command line. Both HP and Dell have issues with Linux.
>>
>> --
>> Tony Baechler, founder, Baechler Access Technology Services
>> Putting accessibility at the forefront of technology
>> mailto:bats at batsupport.com
>> Phone: 1-619-746-8310  SMS text: 1-619-375-2545
>>
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