Ray Butterworth's questions

A µSD card that was in a security camera suddenly stopped recording:

• Much of the data is gone (not a problem).
• The data that is still there is correct and readable.
• The card now always mounts as read-only, (on Chromebook, Windows, and Ubuntu).

I can't reformat it or do much of anything with it:

$ df
/dev/mmcblk0   vfat          117G   15G      102G  13% /media/ray/xxx

$ sudo fdisk -l /dev/mmcblk0
Disk /dev/mmcblk0: 116.1 GiB, 124657860608 bytes, 243472384 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

$ sudo fsck /dev/mmcblk0
fsck from util-linux 2.34
fsck.fat 4.1 (2017-01-24)
open: Read-only file system

$ sudo hdparm -r0 /dev/mmcblk0
/dev/mmcblk0:
 setting readonly to 0 (off)
 readonly      =  1 (on)
$ sudo hdparm -r0 /dev/mmcblk0
/dev/mmcblk0:
 setting readonly to 0 (off)
 readonly      =  1 (on)

$ sudo fsck /dev/mmcblk0
fsck from util-linux 2.34
fsck.fat 4.1 (2017-01-24)
open: Read-only file system

$ sudo umount /media/ray/xxx
$ sudo mount  -o rw  /dev/mmcblk0  /media/ray/xxx
mount: /media/ray/xxx: WARNING: device write-protected, mounted read-only.

Note that this is not a full-sized SD card; there is no physical write-protection switch.

Is the card salvageable, or garbage?

$ od -t x1 <inputfile produces … 0a e2 8c a5 0a ….

The 0a are linefeeds, and e2 8c a5 are the UTF-8 representation of a Unicode character.

For this simple case, I can do it by hand:

[1110]0010  [10]001100  [10]100101  =  10  0011  0010  0101 = 2 3 2 5

What shell command line can convert e2 8c a5 or e28ca5 into 2325?

(For completeness, converting the other way would be good to know too.)

This is a duplicate of 11.04 - UPNP Media server? - Ask Ubuntu, but its answer is over a decade old.

Specifically, we currently have a Windows laptop with WMP acting as a server to a Yamaha RX-A780 receiver (and to other devices). Configuration was as simple as clicking on a button to allow sharing, but it can be slow to respond (and I prefer not to use Windows anyway).

Instead, I want my Ubuntu desktop to be the music server for a large /data/Music directory.

I tried kodi, and it works, but:Tour - Software Recommendations Stack Exchange

• it is massive overkill (I don't need movies, games, weather reports, etc.)
• its graphics interface isn't intuitive.
• how to find the specific parts that I want within all the other parts that I don't want isn't obvious.

And more significantly:

• it continuously burns 10% of my CPU 24 hours a day, even when not in use.
• it doesn't automatically notice when new albums are added to the directory.

Is there something available for Ubuntu that's much more lightweight, not doing much more than serving up the music when requested?

NOTE:

I have since noticed that there is a Software Recommendations Stack Exchange site.
That would have been a more appropriate place for me to have asked this question.

To avoid accidental damage, my photographs are kept as read-only files (-r--r--r--).

Unfortunately, they appear like this in nautilus:

How can I configure nautilus to not obscure the images with the worse than useless, giant padlock symbol?

UPDATE:

I tried replacing /usr/share/icons/Yaru/256x256/emblems with a link to ../8x8/emblems hoping it would use the smaller icon.

Unfortunately it insisted on using the original huge size, and simply expanded the 8x8 image into a fuzzy padlock.

And of course even that useless fix requires root privileges.

And if the image is also a symlink it gets even worse:

What is the purpose of nautilus if it isn't to browse images in a directory?

This insistence on obscuring the image is really silly.

Whenever I sign onto (or unlock the passworded screen of) a recently installed 20.04 system, /var/log/syslog reports that it is starting the fingerprint authentication daemon:

…
Nov 15 13:29:28 ray-desktop dbus-daemon[528]: [system] Activating via systemd: service name='net.reactivated.Fprint' unit='fprintd.service' requested by ':1.193' (uid=1000 pid=8276 comm="/usr/bin/gnome-shell " label="unconfined")
Nov 15 13:29:28 ray-desktop systemd[1]: Starting Fingerprint Authentication Daemon...
Nov 15 13:29:28 ray-desktop dbus-daemon[528]: [system] Successfully activated service 'net.reactivated.Fprint'
Nov 15 13:29:28 ray-desktop systemd[1]: Started Fingerprint Authentication Daemon.
Nov 15 13:29:29 ray-desktop NetworkManager[86471]: <info>  [1605464969.2480] agent-manager: agent[5d99141cf1aa3382,:1.193/org.gnome.Shell.NetworkAgent/1000]: agent registered
Nov 15 13:29:29 ray-desktop dbus-daemon[8052]: [session uid=1000 pid=8052] Activating service name='org.freedesktop.FileManager1' requested by ':1.42' (uid=1000 pid=8276 comm="/usr/bin/gnome-shell " label="unconfined")
Nov 15 13:29:29 ray-desktop dbus-daemon[8052]: [session uid=1000 pid=8052] Activating service name='org.gnome.Nautilus' requested by ':1.42' (uid=1000 pid=8276 comm="/usr/bin/gnome-shell " label="unconfined")
Nov 15 13:29:29 ray-desktop dbus-daemon[8052]: [session uid=1000 pid=8052] Successfully activated service 'org.gnome.Nautilus'
Nov 15 13:29:29 ray-desktop org.gnome.Nautilus[132137]: Failed to register: Unable to acquire bus name 'org.gnome.Nautilus'
Nov 15 13:29:29 ray-desktop dbus-daemon[8052]: [session uid=1000 pid=8052] Successfully activated service 'org.freedesktop.FileManager1'
…
Nov 15 13:29:58 ray-desktop systemd[1]: fprintd.service: Succeeded.
…

This is a desktop computer with no fingerprint hardware, so why does it run the daemon?

And more importantly, how does one tell the system not to?

This old question sounds like what I want: Copy ubuntu.iso to Usb Stick with two partitions

It's marked as a duplicate of: How do I install Ubuntu to a USB key? (without using Startup Disk Creator)

But the answers all answer a different question, how to create a bootable USB with multiple partitons.

I don't want something that is simply bootable; I want to have something that can be used to install Ubuntu (what I would get if I simply used dd to copy the iso) but the USB stick should also have one or more writable partitions in addition to what is in the iso.

When rebooting (18.04), my screen stayed black until the actual login appeared.

It seems that the:

GRUB_GFXMODE=640x480

line in /etc/default/grub had reverted back to being a commented-out line.

The file was dated August 4 at 8:11:32, which according to /varlog/dpkg/log is when a software update occurred:

…
2020-08-04 08:11:32 configure ubuntu-release-upgrader-gtk:all 1:18.04.38 <none>
2020-08-04 08:11:32 status unpacked ubuntu-release-upgrader-gtk:all 1:18.04.38
2020-08-04 08:11:32 status half-configured ubuntu-release-upgrader-gtk:all 1:18.04.38
2020-08-04 08:11:32 status installed ubuntu-release-upgrader-gtk:all 1:18.04.38
2020-08-04 08:11:32 configure grub-pc:amd64 2.02-2ubuntu8.17 <none>
2020-08-04 08:11:32 status unpacked grub-pc:amd64 2.02-2ubuntu8.17
2020-08-04 08:11:32 status unpacked grub-pc:amd64 2.02-2ubuntu8.17
2020-08-04 08:11:32 status unpacked grub-pc:amd64 2.02-2ubuntu8.17
2020-08-04 08:11:32 status half-configured grub-pc:amd64 2.02-2ubuntu8.17
2020-08-04 08:11:34 status installed grub-pc:amd64 2.02-2ubuntu8.17
2020-08-04 08:11:34 configure grub-efi-amd64-signed:amd64 1.93.19+2.02-2ubuntu8.17 <none>
2020-08-04 08:11:34 status unpacked grub-efi-amd64-signed:amd64 1.93.19+2.02-2ubuntu8.17
2020-08-04 08:11:34 status half-configured grub-efi-amd64-signed:amd64 1.93.19+2.02-2ubuntu8.17
2020-08-04 08:11:35 status installed grub-efi-amd64-signed:amd64 1.93.19+2.02-2ubuntu8.17
2020-08-04 08:11:35 trigproc systemd:amd64 237-3ubuntu10.41 <none>
…

It doesn't make sense that an update would overwrite this file, which is intended to contain locally edited configuration.

Was that a one time mistake, or is there something I'm supposed to do to prevent this from happening again, or what?

Using Ubuntu 18.04, on both Chrome and Firefox, when I copy and paste text, the quotation marks around <q> tagged text are lost. Notice that all the words are selected, but the two quotation marks aren't. So when I paste the text, the quotation marks don't appear in the result:

The word xxx is inside a <q> tag.

Is this something I have somehow configured incorrectly?

$ cut -d' ' -f5 /var/log/syslog.1 | sed -e 's/\[.*//' | sort | uniq -c | sort -n
  1  colord
  1  cracklib:
  1  update-notifier.desktop
  2  avahi-daemon
  2  gsd-color
  3  dhclient
  5  PackageKit:
  6  nm-dispatcher:
  7  whoopsie
  8  snapd
 12  NetworkManager
 14  dbus-daemon
 20  gvfsd-metadata
 29  smartd
 40  gnome-shell
 53  anacron
 78  gnome-software
 78  systemd
174  CRON
725  org.gnome.Shell.desktop

More than two thirds of the syslog entries are from gnome.

For Ubuntu 18.04, is this:

• normal.
• normal, but configurable to report only the significant events.
• broken, something needs to be changed.

My machine has lots of memory, so I moved ~/.cache/google-chrome into /tmp, which is a tmpfs RAM disk. This makes the browser run faster and reduces SSD usage. When I reboot, it all goes away, but it gets recreated again. All is fine.

In theory, I could move all of ~/.cache there too.

But in practice, how likely is it that some packages (ab)use ~/.cache for something other than temporary reproducible data?

UPDATE:

I decided to try it out and did this:

$ mv ~/.cache ~/.cache.old
$ ln  -s  /tmp/home/ray/.cache  ~/.

and then added this to my ~/.profile:

mkdir  -p  /tmp/home/ray/.cache

and so far everything is working okay across reboots. Removing .cache.old will free up about 2G of mostly ancient files.

If I ever do run into any packages that misuse .cache, I can teach .profile to add a symlink back to a real directory for that specific case.

ras-mc-ctl --errors is reporting results like:

661 2019-08-20 08:42:29 -0400 error: corrected filtering (some unreported errors in same region) Generic CACHE Level-3 Generic Error, mcg mcgstatus=0, mci Corrected_error Threshold based error status: yellow, mcgcap=0x00000c09, status=0x8c400c400001110b, addr=0x3334c0000080b06, misc=0x00b501c0, tsc=0x3c6571e2bbea4, walltime=0x5d5beab4, cpuid=0x000806e9, bank=0x00000008

and more frequently:

728 2019-08-31 13:35:59 -0400 error: corrected filtering (some unreported errors in same region) Generic CACHE Level-3 Generic Error, mcg mcgstatus=0, mci Corrected_error Threshold based error status: green, Large number of corrected cache errors. System operating, but might leadto uncorrected errors soon, mcgcap=0x00000c09, status=0x8c2000c00001110b, addr=0x2b6b100000374cf, misc=0x0001bdc0, tsc=0x376c4b0d8828, walltime=0x5d6aafff, cpuid=0x000806e9, bank=0x00000008

What do these messages actually mean, and what could/should one do about them?

Additional info:

• This is an Intel NUC 7i7BNH, with 16 Gb memory, 500G SSD, and 4K monitor.
• It runs Ubuntu 18.0, with recent "apt upgrade".
• The BIOS was updated to the recent July version.
• I've made no hardware modifications.

lshw -C memory shows:

*-firmware                
    description: BIOS
    vendor: Intel Corp.
    physical id: 0
    version: BNKBL357.86A.0080.2019.0725.1139
    date: 07/25/2019
    size: 64KiB
    capacity: 8128KiB
    capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int14serial int17printer acpi usb biosbootspecification uefi
*-memory
    description: System Memory
    physical id: 28
    slot: System board or motherboard
    size: 16GiB
    *-bank:0
        description: SODIMM DDR4 Synchronous Unbuffered (Unregistered) 2133 MHz (0.5 ns)
        product: CMSO16GX4M1A2133C15
        vendor: AMI
        physical id: 0
        serial: 00000000
        slot: ChannelA-DIMM0
        size: 16GiB
        width: 64 bits
        clock: 2133MHz (0.5ns)
    *-bank:1
        description: [empty]
        physical id: 1
        slot: ChannelB-DIMM0
*-cache:0
    description: L1 cache
    physical id: 2d
    slot: L1 Cache
    size: 128KiB
    capacity: 128KiB
    capabilities: synchronous internal write-back unified
    configuration: level=1
*-cache:1
    description: L2 cache
    physical id: 2e
    slot: L2 Cache
    size: 512KiB
    capacity: 512KiB
    capabilities: synchronous internal write-back unified
    configuration: level=2
*-cache:2
    description: L3 cache
    physical id: 2f
    slot: L3 Cache
    size: 4MiB
    capacity: 4MiB
    capabilities: synchronous internal write-back unified
    configuration: level=3
*-memory UNCLAIMED
    description: Memory controller
    product: Sunrise Point-LP PMC
    vendor: Intel Corporation
    physical id: 1f.2
    bus info: pci@0000:00:1f.2
    version: 21
    width: 32 bits
    clock: 33MHz (30.3ns)
    capabilities: bus_master
    configuration: latency=0
    resources: memory:dc244000-dc247fff

Test results:

Running memtest86 produced some interesting results:

• After about 5 minutes, it displayed the Intel logo and rebooted.
• The same thing happened again, but I managed to record most of the messages first.
• The third time, it completed a full pass (about 45 minutes), and then crashed again a few minutes into the second pass.
• I'll leave it running, but I doubt it will make it through 4 passes.

The second attempt resulted in:

Test 4: Addr: 33090D380 Expected 08080808 Actual: 18080808 CPU:2
Test 4: Addr: 33090D38C Expected 08080808 Actual: 08080818 CPU:2
Test 4: Addr: 33090D390 Expected 08080808 Actual: [???]
Test 4: Addr: 33090D394 Expected 08080808 Actual: [???]

The third time, which made it through the first pass, showed:

Note that the addresses aren't the same as the previous time (though both had 4 errors).

I recently created a RAM /tmp by adding this to /etc/fstab:

tmpfs /tmp tmpfs rw,nosuid,nodev,noatime   0    0

Everything works fine, and in theory the system runs faster now, but at boot time /var/log/syslog gets:

… tmp.mount: Directory /tmp to mount over is not empty, mounting anyway.

This situation seems inevitable, as there is never an opportunity to remove files from the filesystem version of /tmp.

The wasted space is trivial, but as a matter of interest, is there any easy way to clean out the junk hidden under the /tmp mountpoint?

My Ubuntu 18.04 system randomly freezes for several seconds and then reboots. Sometimes it's okay for a week or two, and sometimes it happens twice in the same day:

=====  2019-06-27 20:58:30 -0400 Thu
=====  2019-06-28 09:31:13 -0400 Fri
=====  2019-06-29 12:39:59 -0400 Sat
=====  2019-07-02 08:45:18 -0400 Tue
=====  2019-07-07 00:11:12 -0400 Sun
=====  2019-07-10 01:18:48 -0400 Wed
=====  2019-07-10 01:23:30 -0400 Wed
=====  2019-07-18 20:42:12 -0400 Thu
=====  2019-07-22 09:23:59 -0400 Mon
=====  2019-07-22 19:47:52 -0400 Mon
=====  2019-07-22 20:50:15 -0400 Mon
=====  2019-07-23 19:30:48 -0400 Tue
=====  2019-07-24 18:48:29 -0400 Wed
=====  2019-07-25 19:52:52 -0400 Thu

Tonight it happened when I wasn't even home, so it was basically doing nothing at the time.

All the software has been updated recently ("apt update" and "apt upgrade").

I've been logging the temperature at reboot time, and it's typically not especially high. E.g.:

Package id 0:  +65.0°C  (high = +100.0°C, crit = +100.0°C)
Core 0:        +65.0°C  (high = +100.0°C, crit = +100.0°C)
Core 1:        +64.0°C  (high = +100.0°C, crit = +100.0°C)
temp1:         +53.0°C

It has 16G of memory, so there's lots available.

I replaced the memory card recently to see if that could be causing it, but the change had no effect.

/var/adm/syslog shows little activity, and then suddenly shows the reboot.

This time, shortly before the reboot, there were error messages from "gsd-housekeepin", but that's not always the case.

There are no message after that (19:49:23) for another 3 minutes, and then the reboot at (19:52:52):

...
Jul 25 19:20:34 ray-desktop org.gnome.Shell.desktop[1568]: #23 0x7ffc1c6d7730 b   resource:///org/gnome/gjs/modules/_legacy.js:82 (0x7f72c84b5de0 @ 71)
Jul 25 19:20:34 ray-desktop org.gnome.Shell.desktop[1568]: #24 0x562f516643f0 i   resource:///org/gnome/shell/ui/screenShield.js:854 (0x7f72abc505e8 @ 25)
Jul 25 19:20:34 ray-desktop gnome-software[1961]: no app for changed [email protected]
Jul 25 19:20:34 ray-desktop gnome-software[1961]: no app for changed [email protected]
Jul 25 19:25:01 ray-desktop CRON[26107]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jul 25 19:35:01 ray-desktop CRON[26181]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jul 25 19:45:01 ray-desktop CRON[26247]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-rtkit-daemon.service-rOQu2D: Error opening directory '/var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-rtkit-daemon.service-rOQu2D': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-colord.service-3zmTxO: Error opening directory '/var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-colord.service-3zmTxO': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-fwupd.service-P4UoAn: Error opening directory '/var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-fwupd.service-P4UoAn': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-bolt.service-dsge7s: Error opening directory '/var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-bolt.service-dsge7s': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-ModemManager.service-1PtGCs: Error opening directory '/var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-ModemManager.service-1PtGCs': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-systemd-resolved.service-vNNHBN: Error opening directory '/var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-systemd-resolved.service-vNNHBN': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-systemd-timesyncd.service-ftiEu9: Error opening directory '/var/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-systemd-timesyncd.service-ftiEu9': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /tmp/.com.google.Chrome.deklZp: Error opening directory '/tmp/.com.google.Chrome.deklZp': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-bolt.service-a96unv: Error opening directory '/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-bolt.service-a96unv': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-systemd-resolved.service-qLTayY: Error opening directory '/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-systemd-resolved.service-qLTayY': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-rtkit-daemon.service-kv3biJ: Error opening directory '/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-rtkit-daemon.service-kv3biJ': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-ModemManager.service-EO4b7C: Error opening directory '/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-ModemManager.service-EO4b7C': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-systemd-timesyncd.service-awJNrk: Error opening directory '/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-systemd-timesyncd.service-awJNrk': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-fwupd.service-SoSJWr: Error opening directory '/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-fwupd.service-SoSJWr': Permission denied
Jul 25 19:49:23 ray-desktop gsd-housekeepin[1722]: Failed to enumerate children of /tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-colord.service-EcYRyY: Error opening directory '/tmp/systemd-private-cb9f998457344f9ea2b392c8a5517e35-colord.service-EcYRyY': Permission denied
Jul 25 19:52:52 ray-desktop systemd-modules-load[257]: Inserted module 'lp'
Jul 25 19:52:52 ray-desktop blkmapd[292]: open pipe file /run/rpc_pipefs/nfs/blocklayout failed: No such file or directory
Jul 25 19:52:52 ray-desktop systemd-modules-load[257]: Inserted module 'ppdev'
Jul 25 19:52:52 ray-desktop systemd-modules-load[257]: Inserted module 'parport_pc'
Jul 25 19:52:52 ray-desktop systemd-modules-load[257]: Inserted module 'coretemp'
Jul 25 19:52:52 ray-desktop systemd-sysctl[290]: Couldn't write '10' to 'sysctl vm/swappiness', ignoring: No such file or directory
Jul 25 19:52:52 ray-desktop systemd[1]: Starting Flush Journal to Persistent Storage...
Jul 25 19:52:52 ray-desktop systemd[1]: Started udev Kernel Device Manager.
Jul 25 19:52:52 ray-desktop systemd[1]: Started Dispatch Password Requests to Console Directory Watch.
Jul 25 19:52:52 ray-desktop systemd[1]: Reached target Local Encrypted Volumes.
Jul 25 19:52:52 ray-desktop systemd[1]: Started Flush Journal to Persistent Storage.
Jul 25 19:52:52 ray-desktop systemd[1]: Activated swap /swapfile.
Jul 25 19:52:52 ray-desktop systemd[1]: Reached target Swap.
Jul 25 19:52:52 ray-desktop mtp-probe: checking bus 1, device 7: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3.3"
Jul 25 19:52:52 ray-desktop mtp-probe: bus: 1, device: 7 was not an MTP device
Jul 25 19:52:52 ray-desktop mtp-probe: checking bus 1, device 6: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3.2"
Jul 25 19:52:52 ray-desktop systemd-udevd[312]: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Jul 25 19:52:52 ray-desktop mtp-probe: checking bus 1, device 3: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-4"
Jul 25 19:52:52 ray-desktop mtp-probe: bus: 1, device: 3 was not an MTP device
Jul 25 19:52:52 ray-desktop mtp-probe: checking bus 1, device 4: "/sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3.1"
Jul 25 19:52:52 ray-desktop mtp-probe: bus: 1, device: 4 was not an MTP device
Jul 25 19:52:52 ray-desktop mtp-probe: bus: 1, device: 6 was not an MTP device
Jul 25 19:52:52 ray-desktop systemd-udevd[304]: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Jul 25 19:52:52 ray-desktop systemd[1]: Listening on Load/Save RF Kill Switch Status /dev/rfkill Watch.
Jul 25 19:52:52 ray-desktop systemd[1]: Starting Load/Save RF Kill Switch Status...
Jul 25 19:52:52 ray-desktop systemd[1]: Started Load/Save RF Kill Switch Status.
Jul 25 19:52:52 ray-desktop systemd[1]: Reached target Sound Card.
Jul 25 19:52:52 ray-desktop systemd-udevd[309]: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Jul 25 19:52:52 ray-desktop systemd[1]: Found device Samsung_SSD_850_EVO_500GB EFI\x20System\x20Partition.
Jul 25 19:52:52 ray-desktop systemd[1]: Started Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling.
Jul 25 19:52:52 ray-desktop systemd[1]: Reached target Local File Systems (Pre).
Jul 25 19:52:52 ray-desktop systemd[1]: Starting File System Check on /dev/disk/by-uuid/046A-4D3B...
...

Any idea what could be causing this, or what I could do to investigate?

EDIT:

It just happened again, this time without any freeze at all.

I was typing and suddenly the boot screen appeared.

The syslog shows nothing for two minutes before that:

Jul 27 22:55:01 ray-desktop CRON[6661]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jul 27 23:04:52 ray-desktop systemd[1]: Started Run anacron jobs.
Jul 27 23:04:52 ray-desktop anacron[6716]: Anacron 2.3 started on 2019-07-27
Jul 27 23:04:52 ray-desktop anacron[6716]: Normal exit (0 jobs run)
Jul 27 23:05:01 ray-desktop CRON[6720]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jul 27 23:15:01 ray-desktop CRON[6770]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jul 27 23:17:01 ray-desktop CRON[6784]: (root) CMD (root    cd / && run-parts --report /etc/cron.hourly)
Jul 27 23:17:01 ray-desktop CRON[6785]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)
Jul 27 23:17:01 ray-desktop CRON[6783]: (CRON) info (No MTA installed, discarding output)
Jul 27 23:24:57 ray-desktop gnome-software[1930]: no app for changed [email protected]
Jul 27 23:24:57 ray-desktop gnome-software[1930]: no app for changed [email protected]
Jul 27 23:24:57 ray-desktop gvfsd-metadata[1586]: g_udev_device_has_property: assertion 'G_UDEV_IS_DEVICE (device)' failed
Jul 27 23:24:57 ray-desktop gvfsd-metadata[1586]: g_udev_device_has_property: assertion 'G_UDEV_IS_DEVICE (device)' failed
Jul 27 23:24:57 ray-desktop gnome-shell[1518]: [AppIndicatorSupport-DEBUG] Registering StatusNotifierItem :1.81/org/ayatana/NotificationItem/software_update_available
Jul 27 23:24:57 ray-desktop gnome-shell[1518]: [AppIndicatorSupport-DEBUG] Registering StatusNotifierItem :1.81/org/ayatana/NotificationItem/livepatch
Jul 27 23:25:01 ray-desktop CRON[6846]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jul 27 23:27:05 ray-desktop kernel: [    0.000000] microcode: microcode updated early to revision 0xb4, date = 2019-04-01
Jul 27 23:27:05 ray-desktop kernel: [    0.000000] Linux version 4.15.0-55-generic (buildd@lcy01-amd64-029) (gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)) #60-Ubuntu SMP Tue Jul 2 18:22:20 UTC 2019 (Ubuntu 4.15.0-55.60-generic 4.15.18)
Jul 27 23:27:05 ray-desktop kernel: [    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-55-generic root=UUID=a149eb1a-46b2-4403-b5e5-4cf8b2a1bbb9 ro quiet acpi_osi=!
Jul 27 23:27:05 ray-desktop kernel: [    0.000000] KERNEL supported cpus:
Jul 27 23:27:05 ray-desktop kernel: [    0.000000]   Intel GenuineIntel
Jul 27 23:27:05 ray-desktop kernel: [    0.000000]   AMD AuthenticAMD
Jul 27 23:27:05 ray-desktop kernel: [    0.000000]   Centaur CentaurHauls

I'm running Ubuntu 18.04 on an Intel NUC 7i7BNH, with 16G of memory, which is far more than I would normally use (e.g. there's 12G free now).

I've just obtained another 16G card from retired hardware.

The question is, is there any advantage or disadvantage to installing that extra memory in my NUC? Would it even ever get used?

On Ubuntu 18.04.2 LTS, when I use the "File" GUI to browse the filesystem, the timestamps are displayed very inconsistently:

Seeing at least four different formats is more than a little confusing when visually scanning through the list.

Is there some way to get a consistent format?

("yyyy-mm-dd hh:mm:ss" would be ideal, but anything that's uniform would be an improvement).

Using Google Chrome on Ubuntu 18.04, I sometimes see pages that appear like this:

Downloading the source and viewing it in "vim" shows:

(The characters in the source need to be read right-to-left.)

The hexdump command shows:

0000000   <   s   t   r   o   n   g   >   �   �   �   �   �   �   �   �
0000000    733c    7274    6e6f    3e67    a0d7    b4d6    aad7    bcd6
0000010   �   �   �   �   � 227   � 225   �   �   <   /   s   t   r   o  
0000010    b0d6    a7d7    97d6    95d7    bcd6    2f3c    7473    6f72  
0000020   n   g   >       � 233   �   �   �   �   �   �   �   �   � 225  
0000020    676e    203e    9bd7    bcd6    b7d6    a4d7    bcd6    95d7  
0000030   �   �   �   �   � 231       �   �   �   �   � 222   �   �   �  
0000030    b9d6    aad7    99d6    d720    d6a8    d7b7    d692    d7b0  
0000040 234   �   �   �   �   � 231       � 224   �   �   � 233   �   �  
0000040    d69c    d6b5    d7a3    2099    94d7    b7d6    9bd7    bcd6  
0000050   �   �   � 224   �   �   �   �   �   �   � 224   � 231   � 235  
0000050    b9d6    94d7    b2d6    a0d7    b4d6    94d6    99d7    9dd7  
0000060       � 220   �   �   � 226   � 234       � 224   �   �   � 227  
0000060    d720    d690    d6b6    d796    209c    94d7    b6d6    97d7  
0000070   �   �   �   �   �   �   � 221   �   �   � 221   � 224       <  
0000070    b8d6    a8d7    b8d6    91d7    b8d6    91d6    94d7    3c20  
0000080   /   p   >  \n                                            
0000080    702f    0a3e                  

Six of the characters each appear as multiple unknown characters on the web page. Am I missing some font, or is this a bug in Google Chrome, or in Ubuntu, or what?

If my printer is turned off, lpr still works fine, lpq shows the job in the print queue, and if I turn on the printer the job prints okay.

But if I wait a few hours though, lpr shows that the queue is empty and my print job has disappeared, so obviously something is automatically deleting old print jobs.

What controls that automated deletion, and how can I configure it to wait longer?

% journalctl
...
Dec 14 22:37:30 ray-desktop kernel: mce: [Hardware Error]: Machine check events logged
-- Reboot --
Dec 14 22:40:08 ray-desktop kernel: microcode: microcode updated early to revision 0x8e, date = 2018-03-24
...

/var/log/kern.log has:

...
Dec 14 22:37:30 ray-desktop kernel: [539775.847567] mce: [Hardware Error]: Machine check events logged
Dec 14 22:40:09 ray-desktop kernel: [    0.000000] microcode: microcode updated early to revision 0x8e, date = 2018-03-24
Dec 14 22:40:09 ray-desktop kernel: [    0.000000] Linux version 4.15.0-42-generic (buildd@lgw01-amd64-023) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #45-Ubuntu SMP Thu Nov 15 19:32:57 UTC 2018 (Ubuntu 4.15.0-42.45-generic 4.15.18)
...

But Ubuntu 18.04 has no mcelog command or /var/log/mcelog file.

So where are the events logged?

Or more generally, how do I determine what hardware failed?