eridani's questions

After swapping a faulty router, trying to ssh from PC "A" (Ubuntu 20.04.6) to PC "A", produces the error message: ssh: Could not resolve hostname pca.local: Name or service not known. ping and other such commands can't find the host either.

However, hostname connections from other devices like "pcb" to pca.local, "pca" to pcb.local, "pcb" to pcb.local work. Same with "pca" to "pca" via IP address. Interestingly, connections from "pca" to pca, without the .local, actually work!

But that is useless to me because it is already known in scripts and whatnot as pca.local. All devices in the LAN preserved their IP addresses across router changes.

What I have tried:

• cat /etc/hostname shows its own name as expected.
• systemctl restart systemd-resolved.
• /etc/init.d/networking restart.
• dhclient -r eth0.
• Can't reboot that machine for a few days.

The output of service avahi-daemon status

● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
     Loaded: loaded (/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2024-06-12 12:44:47 CST; 1h 49min ago
TriggeredBy: ● avahi-daemon.socket
   Main PID: 163913 (avahi-daemon)
     Status: "avahi-daemon 0.7 starting up."
      Tasks: 2 (limit: 4383)
     Memory: 1.3M
     CGroup: /system.slice/avahi-daemon.service
             ├─163913 avahi-daemon: registering [pca.local]
             └─163914 avahi-daemon: chroot helper

jun 12 12:44:47 pca avahi-daemon[163913]: Server startup complete. Host name is pca.local. Local service cookie is 2927830272.
jun 12 12:44:47 pca avahi-daemon[163913]: Failed to parse address 'fe80::1%eth0', ignoring.
jun 12 13:08:25 pca avahi-daemon[163913]: Withdrawing address record for fe80::342a:68ff:fec8:fa4e on veth2964dfb.
jun 12 13:08:28 pca avahi-daemon[163913]: Registering new address record for fe80::a881:e7ff:fec7:ead3 on veth6ddcaf7.*.
jun 12 13:34:33 pca avahi-daemon[163913]: Withdrawing address record for fe80::a881:e7ff:fec7:ead3 on veth6ddcaf7.
jun 12 13:34:35 pca avahi-daemon[163913]: Registering new address record for fe80::5c62:9eff:fe29:543e on veth31f1578.*.
jun 12 13:53:37 pca avahi-daemon[163913]: Withdrawing address record for fe80::5c62:9eff:fe29:543e on veth31f1578.
jun 12 13:53:40 pca avahi-daemon[163913]: Registering new address record for fe80::c0eb:52ff:fe22:656d on veth6d79f34.*.
jun 12 14:26:11 pca avahi-daemon[163913]: Withdrawing address record for fe80::c0eb:52ff:fe22:656d on veth6d79f34.
jun 12 14:26:13 pca avahi-daemon[163913]: Registering new address record for fe80::2ce3:93ff:fe4e:8b6f on vethd1fb373.*.

The output of ip addr show dev eth0

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 6a:55:c4:0f:59:ba brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.94/24 brd 192.168.1.255 scope global noprefixroute eth0
       valid_lft forever preferred_lft forever
    inet6 2806:107e:15:413d:bdc8:3b3e:88ec:370e/64 scope global temporary dynamic 
       valid_lft 540279sec preferred_lft 21774sec
    inet6 2806:107e:15:413d:c92f:8f13:fca8:2576/64 scope global temporary deprecated dynamic 
       valid_lft 453986sec preferred_lft 0sec
    inet6 2806:107e:15:413d:7893:65ce:cb5a:a28c/64 scope global dynamic mngtmpaddr noprefixroute 
       valid_lft 2441181sec preferred_lft 2441181sec
    inet6 fe80::4455:f83b:22ee:5769/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

Output of avahi-resolve-host-name pca.local

pca.local  192.168.1.94

Output of cat /etc/avahi/avahi-daemon.conf | grep -v "#"

[server]
use-ipv4=yes
use-ipv6=no
ratelimit-interval-usec=1000000
ratelimit-burst=1000

[wide-area]
enable-wide-area=yes

[publish]
publish-hinfo=no
publish-workstation=no

[reflector]

[rlimits]

The output of cat /etc/nsswitch.conf

# /etc/nsswitch.conf
#
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed, try:
# `info libc "Name Service Switch"' for information about this file.

passwd:         files
group:          files
shadow:         files
gshadow:        files

hosts:          files mymachines dns myhostname
networks:       files

protocols:      db files
services:       db files
ethers:         db files
rpc:            db files

netgroup:       nis

I've created a unit to run at user login, but when trying to start it, I get the following error:

/home/myUser/.config/systemd/user/myUnit.service:5: Neither a valid executable name nor an absolute path: $HOME/.local/bin/myProgram

This is ~/.config/systemd/user/myUnit.service:

[Unit]
Description=Some description...

[Service]
ExecStart=$HOME/.local/bin/myProgram
Type=forking

[Install]
WantedBy=default.target

Systemd wants an absolute path, obviously; but is there a way to not hardcode the home directory per every user, and also don't take out the binary outside the user's home?

I believe there should be one, since we are allowed to place user's units inside the user's own home...

I tried updating from 18.04 to 20.04 but something went wrong and the installer told me that my system could have ended up unusable. I think I know the cause (a bunch of third party repos).

Fortunately I have snapper configured to make snapshots for @ and @home so I can just rollback / and try again; but how do I do this, will I need to boot to an Ubuntu's live USB and what commands shall I type?

I can still use my system, but I don't know what will still work once I reboot.

(already downloaded and burned using Etcher to an USB the Ubuntu 20.04 image just in case)

This is a sample list of my current snapshots:

ID 44624 gen 3718354 top level 9006 path .snapshots/88/snapshot
ID 44625 gen 3718355 top level 9007 path @home/.snapshots/88/snapshot
ID 44864 gen 3732417 top level 9006 path .snapshots/93/snapshot
ID 44865 gen 3732418 top level 9007 path @home/.snapshots/93/snapshot
ID 44912 gen 3735056 top level 9006 path .snapshots/94/snapshot
ID 44913 gen 3735057 top level 9007 path @home/.snapshots/94/snapshot

Data is referenced in as many snapshots you take and it will be deleted from disk only if you delete all snapshots that referenced said data as well as the data from the running volume, this holds true for both, btrfs and ZFS.

For example, in btrfs if I create ~/mifyle.txt and then take an snapshot of @home, my file will not be deleted from disk unless I delete this snapshot and ~/myfile.txt, the same happens with ZFS.

But what if I'm taking snapshots from @ and @home? Will ~/myfile.txt be referenced in @ and @home snapshots or just in @home snapshots?

And does ZFS behave differently? If I create a file rpool/home/myfile.txt, where rpool is the parent and rpool/home is a child dataset, then take snapshots for rpool and rpool/home, will myfile.txt be referenced in both datasets snapshots or just in the children dataset snapshot?

I would like to switch between dark and light themes easily (Default Breeze and dark Breeze themes) without having to navigate to System Settings > Global themes > Click on theme > click Apply.

So I was wondering if there existed a way to quickly switch between already installed themes without using the mouse, maybe running a previously made Bash script?

If such a way were feasible then I would be able to fire those scripts with this On/Off plasmoid. So, is there a way to change Global Plasma Theme from the command line?

I installed Elisa music player from Flathub, but it refuses to see my Music partition, so I can't add any music to it's library unless I copy it to /home/my_user/.

Is there a way to give a Flatpak application permission to access non canonical addresses?

Aside from specifying it when compiling it...

Is there a way to open files stored outside /home directory?

For example, I've got a shared disk formatted in ZFS that auto mounts stuff in /Volumes/dataset_name I use it to transfer big projects from and to my Mac. OK, that's a weird case, but can't access anything mounted in /media either and well, now that's kinda...

Also, have to point that isn't about one particular snapped program, I've installed many recommended on OMG Ubuntu to test them and so far none had the ability to open anything outside /home; last case but by no means the only one KeePassXC.

Have tried using symlinks and changing some directories permissions but to no avail.

The menu bar of my Ubuntu 16.04 is presenting continuously problems consisting on seemingly random freezes or interaction lag.

For example, if I click a menu or indicator item, the item will become highlighted but the menu would take several seconds to appear or wont appear at all. Some times, if I continue interacting with many items on the Panel the clock will freeze, then the Dash wont show, then the Alt+Tab wont work, then the whole desktop will become unresponsive (but the applications won't crash). At this point I could switch to tty1 then back to GUI then Unity will crash and restart and I would be able to continue working normally.

Currently I'm using an Nvidia GTX 1060 card with proprietary drivers v.378.13 and I'm almost sure that the problem started when I added this GPU to my PC. Before I only used my i5 4670 integrated Intel HD 4600 and don't remember having this issue.

I'm unsure of the trigger but have noticed that it happens more often after I watch a video (single or many) in full screen, be it Flash in the browser or in MPV. Not always though. Some times I can watch hours and the problem wont show. Or I can watch none and the problem will manifest. I suspect also of hardware accelerated browser since I have always Opera or Firefox open, but nothing conclusive.

I've consulted syslog, Xorg.0.log and lightdm logs for clues, but haven't found anything relevant but I'm just a power user, so might have missed something.

Any clue on how to approach and pinpoint this problem?

Suddenly my Kubuntu 16.04 refuses to write some characters.

Usually I was able to press ´+a = á but now I just get ´a on some applications like Firefox on some other applications like Konsole or Dolphin the accent isn't even displayed and only the a appears.

The single exception is LibreOffice where the input is working as expected.

I've wiped out my single keyboard input method configuration in System preferences > Input > Keyboard > Layout and configured it up again, also have consulted this question, but to no avail.

These are the contents of my locale:

$ locale
LANG=es_MX.UTF-8
LANGUAGE=es_MX:es
LC_CTYPE="es_MX.UTF-8"
LC_NUMERIC="es_MX.UTF-8"
LC_TIME="es_MX.UTF-8"
LC_COLLATE="es_MX.UTF-8"
LC_MONETARY="es_MX.UTF-8"
LC_MESSAGES="es_MX.UTF-8"
LC_PAPER="es_MX.UTF-8"
LC_NAME="es_MX.UTF-8"
LC_ADDRESS="es_MX.UTF-8"
LC_TELEPHONE="es_MX.UTF-8"
LC_MEASUREMENT="es_MX.UTF-8"
LC_IDENTIFICATION="es_MX.UTF-8"
LC_ALL=

This is the output of $ im-config -m

default
ibus
none

none

Since I upgraded my GPU, I removed the Intel's Open Source Technology Center Driver following the procedure from this question.

By doing so a bunch of software was downgraded as expected but some other kinda unrelated were removed.

The following packages were automatically installed and are no longer required:
  gnome-software-common libgtkspell3-3-0 libmowgli-2-0 libqt5keychain1 libqtkeychain1 libsnapd-glib1
  snapd-login-service
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
  gnome-software libnvpair1 libuutil1 libzfs2 libzpool2 ubuntu-software ubuntu-zfs zfsutils
The following NEW packages will be installed:
  autoconf automake autopoint dh-autoreconf libcrypto++9v5 libltdl-dev libqt5keychain0 libtool libuv1 m4
The following packages will be upgraded:
  appstream debhelper libappstream4 libarchive13
The following packages will be DOWNGRADED:
  libguess1 libowncloudsync0 libshairplay0 mkvtoolnix mkvtoolnix-gui nethogs nodejs owncloud-client
  owncloud-client-l10n spl spl-dkms synergy xboxdrv zfs-dkms zfs-doc

Among those were gnome-software and ubuntu-software. If I try to reinstall them I get a dependency error:

sudo apt install gnome-software ubuntu-software
...
The following packages have unmet dependencies:
 gnome-software : Depends: appstream but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

This is the output of apt policy appstream:

  Installed: 0.10.6-1~ubuntu16.04.1
  Candidate: 0.10.6-1~ubuntu16.04.1
  Version table:
 *** 0.10.6-1~ubuntu16.04.1 100
        100 http://mx.archive.ubuntu.com/ubuntu xenial-backports/main amd64 Packages
        100 /var/lib/dpkg/status
     0.10.3-1~ubuntu16.04~ppa2 500
        500 http://ppa.launchpad.net/kubuntu-ppa/backports/ubuntu xenial/main amd64 Packages
     0.9.4-1ubuntu2 500
        500 http://mx.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
     0.9.4-1 500
        500 http://mx.archive.ubuntu.com/ubuntu xenial/main amd64 Packages

Everything points to the backports repos messing things up, but I find it strange that the developers didn't noticed such an obvious problem and that thought leads me to think that the true problem is somewhere else. What can I do to fix the Software Center?

I'm on Ubuntu Unity x86_64 16.04

I've a Haswell 4670 CPU with Intel Graphics that I've been used for a couple of years.

Recently acquired and physically installed an nVidia GTX 1610 card. But when I plug my monitor onto the card's DVI slot and turn on my system I can't see nothing.

If I login via a VNC application I can see in: System Settings > Details > Overview" That Ubuntu is still using "Intel Haswell Desktop" graphics instead of the nVidia.

So far I've added the ppa:graphics-drivers/ppa PPA and can see on the list at "Software & Updates > Additional Drivers" NVIDIA 367, NVIDIA 370 and X.org Nouveau alongside with the Intel driver.

I can pick from the list any option, but after clicking "Apply" button my choice get unchecked, the check mark goes back to X.org entry and it asks me to restart.

After restarting everything is the same, I can plug my monitor on the MoBo's DVI port and use my system without problem, but if I plug it into the nVidia port the monitor only shows a "No signal message".

If relevant, MoBo is Gigabyte GA-Z87-HD3.

Any hints?

What is the correct way to mount a disk image so all users (guest included) are able to access it?

I'm currently stuck after mounting it with:

sudo mount -o loop,users,ro,offset=262145048576 '/path/Disk Image.img' '/media/guest-Folder/Disk'

My normal user session can access it, but on a guest session I get an error: "This location could not be displayed. You don't have the permissions necessary to view the contents of Disk" while trying to view the contents in Nautilus.

How do I change the Unity's desktop icon size to a custom value?

If I go to Folder view > Edit > Preferences > Icon view > Default zoom lv I can change the size between 400%, 200%, 150%, 100%, 66%, 50% and 33%.

But I would like a size in between 100% and 66%, maybe a 80% e.g.

Is possible to achieve this?

I installed Ubuntu in an empty disk in an UEFI machine, and has been booting directly without any kind of menu or timeout until last week's software update. I would like to keep booting simple, like it was before.

The relevant change I did was moving a disk with an old Linux Deepin installation from a PC that I sold to the same machine with Ubuntu. So now I have 2 disks on the same PC.

And of course at boot I now have a grub menu to select between Ubuntu and Deepin. I don't need this menu since I always use Ubuntu, the Deepin disk has its own grub and I can choose which disk to boot from the BIOS options.

How do I go back to the old boot sequence? I really don't want to disconnect my Deepin disk.

After reading this question I changed some stuff in the /etc/default/grub file, now it looks like this:

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=0
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="noprompt"

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

Then ran sudo update-grub with no problems. But the grub menu and 10 seconds timeout is still present at boot.

It may be relevant to post the partitioning on the Ubuntu disk, since is not the default:

Partition - Mount point - Flags

/dev/sda1 - - bios_grub

/dev/sda2 - /boot/efi - boot,esp

/dev/sda3 - / -

/dev/sda4 - /home -

/dev/sda5 - swap -

I just got an SSD and wanted to migrate my current Ubuntu installation to take advantage of its performance.

So I booted to an Ubuntu live CD, mounted source (ext4) and target (SSD, btrfs mounted with compress-force=zlib,nodatacow,noatime,rw,ssd) drives and began copying files using rsync:

sudo rsync -av --exclude=/home/ '/media/username/source/' '/media/username/target'

# /home stays on HDD for now

Rsync finished the job without problems. The file count is similar (about 1.2 million files average, number obtained by right click > properties on Nautilus), but the resultant copy is 31GB, way larger than the source which is only 18GB.

Checked sizes by various methods:

• df
• Right click > Properties
• btrfs filesystem df
• Baobab

All gave similar results, source is way smaller.

I know that btrfs uses some kind of metadata journal and "shadow copies" of files when COW is on. But COW is off and even if it were on, is the first population of data plus noway 12GB out of 31GB could be metadata; right? o.o

Any idea on WTH is going on? or better yet, how to fix it?

This program doesn't appear in the "Default applications" > "Music" menu at "System settings" > "Details". I know that is posible to manually set every audio format to open with it. But is there a way to make it appear on the menu at System Settings panel?

That way my media keys will work automatically too.

I also know that the media key problem can be sorted out by setting up custom shortcuts but I preffer avoiding that if posible.

My system: Ubuntu 14.04 Unity

UPDATE:

I found what it seems to be the correct file to modify:

~/.local/share/applications/mimeapps.list

The lines under [Default Applications] looked quite suspicious to me...

But... I were lazy and just replaced every "rhythmbox.desktop" for "gmusicbrowser.desktop". Of course that did the trick helping me setting Gmusicbrowser as default music player in the System Settings panel also I can now launch the player by using the corresponding media key. However I couldn't make the other media keys to work (prev/next/play/pause)...

The problem might lie at the time of installation, I think that Gmusicbrowser isn't registering the mime types that can play, therefore Ubuntu can't realize that it is an audio player, so for now it has to be registered manually.

I have a partition formated to btrfs and im willing to store there stuff that I don't use that often but which I need fast access from time to time (some dumps of my PS2 games for now) because I have read that btrfs can work wonders compressing data on the fly.

The thing is even when mounting this partition using the compress-force=zlib option I can't notice any compression work at all.

Currently my /etc/fstab file display the following info for the drive in question:

LABEL=Emu /mnt/Emu btrfs compress-force=zlib,nosuid,nodev,nofail,comment=x-gvfs-show 0 0

The drive mounts fine and data can be written and read back. But no compression work is done, not with old files nor with new ones.

So far I've tested it by doing the following:

$ sudo dd if=/dev/sda6 of='/mnt/Emu/dummy.txt' bs=1M count=1024
$ sudo btrfs fi sync /mnt/Emu
$ sudo du -h '/mnt/Emu/dummy.txt'

This generated a 1 GB file in said drive and told me the size of the file is indeed 1 GB so nothing has been compressed.

Also verified the size after using chattr +c on said dummy file and then defragmenting the file/drive by using btrfs fi defragment on them.

Any pointing?

My systems specs:

• OS: Ubuntu 14.04 x86_64
• Kernel: 3.13.0-40-generic
• Btrfs: v3.12