Request for explanation of error message

[Paul Smith]

On Sun, 2019-07-28 at 19:31 +0000, Mike Marchywka wrote:
>  I keep suggesting to find an entire loop to post- he posted last
> few lines before but it may help to get an entire period or go back
> to first logfile that seemed too big and start there too.
> Although deleting it and catching the new one starting to fill
> may be easier.

Maybe.  In my experience the last lines in the log file are more
relevant and useful than the first ones.  The first ones are usually
just the normal startup information, etc.

It's the last lines that tell you what's wrong now.

Bret Busby wrote:
> See the first message in the thread.

That's the output from /var/log/syslog.  That may or may not be
helpful.  What we need to see is the output from the file that is huge
and keeps growing: /var/log/lightdm/x-0.log

OK I finally found the message:

https://lists.ubuntu.com/archives/ubuntu-users/2019-July/297830.html

All this discussion of logrotate is not useful.  That's for a system
that is behaving normally.  Your system is not behaving normally.

Also the output in /var/log/syslog may or may not be relevant.  We
should ignore it for now.

The important output is what is seen in your ever-growing log file (the
really big one).

There are two things we need to do:

First, get your system back to working.  The only way to do that is get
rid of these huge log files and free up space on the root partition. 
I've discussed how to do that: remove the huge file, then log out and
back in or, of that doesn't work, try rebooting.

However that is only a temporary solution if your log file continues to
grow like this: the disk will just fill up again.  The only way to get
it to stop is to figure out why it's constantly getting those errors.

I saw two messages in the output of the message above:
  (EE) Could not write pid to lock file in /tmp/.tX0-lock
and:
  xf86EnableIOPorts: failed to set IOPL for I/O (Operation not permitted)

The first one is simple enough.  It might have been because your disk
is full, in which case it's a symptom not a cause.  What are the
permissions on these files?  Run this command:

  ls -ald /tmp /tmp/.tX0-lock

and let us know the results.

The second error also appears to be a permissions problem: I googled
for that message and came across a number of issues discussing starting
the X server without root privileges.  However all of them seem to be
from 5+ years ago.  Modern X servers don't require root privileges to
start.

Unfortunately I don't know much about lightdm (I guess you're using
Xubuntu or something like that not standard Ubuntu which uses gdm) so I
can't provide any direct advice.  Maybe your distro still requires root
privileges to start X.

If, after you reboot and your disk is no longer full, you watch the
size of the /var/log/lightdm/x-0.log file and it continues to grow,
please get the last 50 or so lines and send those along; it doesn't
look like 20 or 30 lines will be enough.