root partition full

[jglen490]

I understand your position oshuluvr. It's true that snapshot will run on any native Linux filesystem, and can be useful for recoverability. But no backup tool that retains data on the same device as the source can contribute to reliability.

I kind of like handcrank drills

[oshunluvr]

I'll never understand feeling like there's no need for native file system supported snapshot and backup capability on any kind of system, or the idea that a file system based on a 31+ year old design and relying on a collection of external tools is somehow better.

Not that it will convince anyone, I had two update issues in the last month that took literally 5 seconds and a reboot to resolve because that's all it takes to roll back. Even if EXT4 could do that, it would still be totally basic. Like using a hand-crank drill instead of a power tool.

LOL

[Schwarzer Kater]

Slightly OT:

[…]
And as you may know I'm just not a fan of BTRFS on simple, single user systems.

For LTS releases I don't see the need (yet?) either.
But for something like openSUSE Tumbleweed or Arch having / on btrfs can be a life saver and is very convenient.

[jglen490]

GreyGeek Yes, when using EXT4 with manual partitioning it is necessary to pre-determine how much space to reserve for each partition. It's actually a minor issue - with experience! I do mine every two years coincident with doing a clean install of the latest LTS, and actually for the past few times I've kept my existing scheme, and sizes, and only formatted the / partition. It just works

And as you may know I'm just not a fan of BTRFS on simple, single user systems.

[Robert24]

Sorry for the delay of my answer. I came back home very late both Monday and Tuesday.


oshunluvr Thanks a lot for your detailed answer. I will try to do this as a last resort. For now I will try to re-install firefox as @Schwarzer\ Kater suggested.
Schwarzer Kater Thank your for your detailed answer. I will try the Debian's step by step instructions to start with.

[oshunluvr]

[USER="34079"]
oshunluvr Once I'll have properly backed up my data, could you tell me what I should do to move the contents of /var to the /backup partition and mount /backup as /var instead? Is it something trivial?

The way I've done this is to:

1. Boot to a Live USB (or another install if you have one)
2. Mount the root and /backup partitions
3. Move ALL the contents of /var on the root partition to the /backup partition.
4. Edit /etc/fstab on the root partition and change the mount point of /backup to /var
5. Reboot

Note you move the contents of /var not the /var folder itself. Leave /var in place as an empty folder because t it will become the mount point.

On reboot, you should notice no difference except more free space on the root partition and when you list mounts you'll see /var as a mount.

If you're a super cautious person;

• Instead of moving the files, COPY them into the /backup partition
• Edit fstab and reboot

This will not immediately result in space savings but gives you a chance to test your work.

If the system boots and works fine, then reboot into the Live USB and delete the content of /var on the root partition - again, leave the empty folder behind.
If the system does NOT boot, edit /etc/fstab again on the root partition, reboot, and try to figure out what you did wrong.

[GreyGeek]

Oh ok.
But you can do that with any filesystem format, of course.
...

I believe you missed the point.

When formatting an HD for use using EXT4 you have to determine in advance how many partitions you'll need AND how much space each partition will use.
IF, for example you create partitions for home, root, var, opt and give them each 1/4th of the HD space, you've fixed how many files each can store. If you install a bunch of software in home and receive a msg that home has only 50mb of space left you have a problem that is going to require that you remove some of the software in home OR make backup your data and repartition your HD to give home more space.

During installation of BTRFS on an HD, /dev/sda, a root file system is established, rootfs, which is the top volume. Inside of it is a subvolume called @, which is mounted by fstab as /. IF @home is also created during the install then it is mounted to /home in fstab. Here is the point: rootfs is a reservoir of HD space that both @ and @home can call upon if either begins to run short on space.

Here is where things get sweet. Say you want to create a place to store special data to make archiving, backing up and restoring easier.
You open a konsole and sudo to root. There you mount /dev/sda to /mnt, while your system is running! Listing /mnt shows
/mnt/@
/mnt/@home
Now,
btrfs subvolume create /mnt/@data
Then,
mkdir /data
as a location to mount @data to.
In fstab you add a line that mounts @data to /data during bootup.
Now you store what data you want to save in /data.
Need to back it up? Mount /dev/sda to /mnt and it exposes @data.
btrfs subvol snapshot -r /mnt/@data /mnt/snapshots/@datayyyymmdd

The HD runs out of space ONLY if rootfs runs out of space. When that happens there are methods to move the rootfs to the new system and resize it to fill the new SSD.

And all I've done is scratch the paint to show a slight inkling of what is underneath and makes life easy for BTRFS users.

[Schwarzer Kater]

[…]
Regarding this:

sudo snap remove firefox if you don't insist on using the Snap and install Firefox to the other partition in /home/$USER/Applications (or another place in /home/$USER if you prefer) instead, following Debian' s installation suggestion (https://wiki.debian.org/Firefox#From_Mozilla_binaries).

Will it uninstall firefox? […]

Yes, it will uninstall the Firefox Snap and afterwards you will have to install Firefox from Mozilla.org to your /home partition instead (so be careful to not install it to /opt, which is on your full / partition!).
If you don't need anything from the Firefox Snap (or if you use e.g. a Firefox account to save / sync your bookmarks etc.) you could even sudo snap remove --purge firefox .

If you don't want to use Debian's step-by-step instructions, I could also change my installation script according to your needs - just tell me where in your /home you would like to install Firefox from Mozilla.org: Script to install traditional Firefox.

[Robert24]

Schwarzer Kater Thanks again for your answers. In your first post, you made some suggestions but only the last one was clear to me.

• erase old log files in /var/log

At first I didn't know how to proceed but I noticed that there is a subfolder called /var/log/journal which takes all the space (1.6G) of /var/log. I then followed the advice of jlittle (I had not understood what were these archived journals the first time I saw the message) and ran

sudo journalctl --vacuum-size=50M

which seems to have helped me reclaim 1.5G of memory. So thank you to both of you.

Regarding this:

sudo snap remove firefox if you don't insist on using the Snap and install Firefox to the other partition in /home/$USER/Applications (or another place in /home/$USER if you prefer) instead, following Debian' s installation suggestion (https://wiki.debian.org/Firefox#From_Mozilla_binaries).

Will it uninstall firefox?

oshunluvr Once I'll have properly backed up my data, could you tell me what I should do to move the contents of /var to the /backup partition and mount /backup as /var instead? Is it something trivial?

[Robert24]

Thank you for your answer kubicle
I tried the commands you recommended and here are the outputs:

blabla:~$ dpkg --list | grep xul-ext-ubufox
rc xul-ext-ubufox 3.4-0ubuntu1.17.10.1 all Ubuntu modifications for Firefox

I don't really know how to interpret this output, to be honest.

Then I did the first purge command

(base) blabla:~$ sudo apt purge $(dpkg -l | grep linux-image | awk '/^rc/ {print $2}')
[sudo] password for me:
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following package was automatically installed and is no longer required:
docker-scan-plugin
Use 'sudo apt autoremove' to remove it.
The following packages will be REMOVED:
linux-image-5.15.0-70-generic* linux-image-5.15.0-71-generic* linux-image-5.15.0-72-generic* linux-image-5.15.0-73-generic* linux-image-5.4.0-100-generic*
linux-image-5.4.0-104-generic* linux-image-5.4.0-105-generic* linux-image-5.4.0-107-generic* linux-image-5.4.0-109-generic* linux-image-5.4.0-110-generic*
linux-image-5.4.0-113-generic* linux-image-5.4.0-117-generic* linux-image-5.4.0-120-generic* linux-image-5.4.0-121-generic* linux-image-5.4.0-122-generic*
linux-image-5.4.0-124-generic* linux-image-5.4.0-125-generic* linux-image-5.4.0-126-generic* linux-image-5.4.0-128-generic* linux-image-5.4.0-131-generic*
linux-image-5.4.0-132-generic* linux-image-5.4.0-135-generic* linux-image-5.4.0-136-generic* linux-image-5.4.0-137-generic* linux-image-5.4.0-139-generic*
linux-image-5.4.0-144-generic* linux-image-5.4.0-147-generic* linux-image-5.4.0-42-generic* linux-image-5.4.0-62-generic* linux-image-5.4.0-64-generic*
linux-image-5.4.0-65-generic* linux-image-5.4.0-66-generic* linux-image-5.4.0-67-generic* linux-image-5.4.0-70-generic* linux-image-5.4.0-71-generic*
linux-image-5.4.0-72-generic* linux-image-5.4.0-73-generic* linux-image-5.4.0-74-generic* linux-image-5.4.0-77-generic* linux-image-5.4.0-80-generic*
linux-image-5.4.0-81-generic* linux-image-5.4.0-84-generic* linux-image-5.4.0-86-generic* linux-image-5.4.0-88-generic* linux-image-5.4.0-89-generic*
linux-image-5.4.0-90-generic* linux-image-5.4.0-91-generic* linux-image-5.4.0-92-generic* linux-image-5.4.0-94-generic* linux-image-5.4.0-96-generic*
linux-image-5.4.0-97-generic* linux-image-5.4.0-99-generic*
0 upgraded, 0 newly installed, 52 to remove and 60 not upgraded.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] Y
(Reading database ... 355874 files and directories currently installed.)
Purging configuration files for linux-image-5.4.0-113-generic (5.4.0-113.127) ...
Purging configuration files for linux-image-5.4.0-71-generic (5.4.0-71.79) ...
Purging configuration files for linux-image-5.4.0-122-generic (5.4.0-122.138) ...
Purging configuration files for linux-image-5.4.0-77-generic (5.4.0-77.86) ...
Purging configuration files for linux-image-5.4.0-147-generic (5.4.0-147.164) ...
Purging configuration files for linux-image-5.4.0-131-generic (5.4.0-131.147) ...
Purging configuration files for linux-image-5.4.0-105-generic (5.4.0-105.119) ...
Purging configuration files for linux-image-5.4.0-120-generic (5.4.0-120.136) ...
Purging configuration files for linux-image-5.4.0-125-generic (5.4.0-125.141) ...
Purging configuration files for linux-image-5.4.0-135-generic (5.4.0-135.152) ...
Purging configuration files for linux-image-5.4.0-97-generic (5.4.0-97.110) ...
Purging configuration files for linux-image-5.4.0-66-generic (5.4.0-66.74) ...
Purging configuration files for linux-image-5.4.0-107-generic (5.4.0-107.121) ...
Purging configuration files for linux-image-5.4.0-92-generic (5.4.0-92.103) ...
Purging configuration files for linux-image-5.4.0-132-generic (5.4.0-132.148) ...
Purging configuration files for linux-image-5.4.0-89-generic (5.4.0-89.100) ...
Purging configuration files for linux-image-5.15.0-71-generic (5.15.0-71.78) ...
Purging configuration files for linux-image-5.4.0-80-generic (5.4.0-80.90) ...
Purging configuration files for linux-image-5.4.0-139-generic (5.4.0-139.156) ...
Purging configuration files for linux-image-5.4.0-144-generic (5.4.0-144.161) ...
Purging configuration files for linux-image-5.4.0-90-generic (5.4.0-90.101) ...
Purging configuration files for linux-image-5.4.0-121-generic (5.4.0-121.137) ...
Purging configuration files for linux-image-5.4.0-67-generic (5.4.0-67.75) ...
Purging configuration files for linux-image-5.4.0-65-generic (5.4.0-65.73) ...
Purging configuration files for linux-image-5.4.0-73-generic (5.4.0-73.82) ...
Purging configuration files for linux-image-5.4.0-100-generic (5.4.0-100.113) ...
Purging configuration files for linux-image-5.4.0-126-generic (5.4.0-126.142) ...
Purging configuration files for linux-image-5.4.0-72-generic (5.4.0-72.80) ...
Purging configuration files for linux-image-5.4.0-84-generic (5.4.0-84.94) ...
Purging configuration files for linux-image-5.4.0-70-generic (5.4.0-70.78) ...
Purging configuration files for linux-image-5.4.0-124-generic (5.4.0-124.140) ...
Purging configuration files for linux-image-5.15.0-70-generic (5.15.0-70.77) ...
Purging configuration files for linux-image-5.15.0-72-generic (5.15.0-72.79) ...
Purging configuration files for linux-image-5.4.0-99-generic (5.4.0-99.112) ...
Purging configuration files for linux-image-5.4.0-74-generic (5.4.0-74.83) ...
Purging configuration files for linux-image-5.4.0-64-generic (5.4.0-64.72) ...
Purging configuration files for linux-image-5.4.0-109-generic (5.4.0-109.123) ...
Purging configuration files for linux-image-5.4.0-104-generic (5.4.0-104.118) ...
Purging configuration files for linux-image-5.4.0-117-generic (5.4.0-117.132) ...
Purging configuration files for linux-image-5.15.0-73-generic (5.15.0-73.80) ...
Purging configuration files for linux-image-5.4.0-128-generic (5.4.0-128.144) ...
Purging configuration files for linux-image-5.4.0-137-generic (5.4.0-137.154) ...
Purging configuration files for linux-image-5.4.0-91-generic (5.4.0-91.102) ...
Purging configuration files for linux-image-5.4.0-110-generic (5.4.0-110.124) ...
Purging configuration files for linux-image-5.4.0-81-generic (5.4.0-81.91) ...
Purging configuration files for linux-image-5.4.0-42-generic (5.4.0-42.46) ...
Purging configuration files for linux-image-5.4.0-136-generic (5.4.0-136.153) ...
Purging configuration files for linux-image-5.4.0-62-generic (5.4.0-62.70) ...
Purging configuration files for linux-image-5.4.0-86-generic (5.4.0-86.97) ...
Purging configuration files for linux-image-5.4.0-88-generic (5.4.0-88.99) ...
Purging configuration files for linux-image-5.4.0-94-generic (5.4.0-94.106) ...
Purging configuration files for linux-image-5.4.0-96-generic (5.4.0-96.109) ...

and then the second:

blabla:~$ dpkg --list | awk '/^rc/ {print $2}' | sudo xargs dpkg --purge
(Reading database ... 355874 files and directories currently installed.)
Purging configuration files for bsdmainutils (12.1.7+nmu3ubuntu2) ...
Purging configuration files for cracklib-runtime (2.9.6-3.4build4) ...
Purging configuration files for crda (3.18-1build1) ...
Purging configuration files for fuse (2.9.9-3) ...
Purging configuration files for ibus (1.5.26-4) ...
Purging configuration files for ippusbxd (1.34-2ubuntu1) ...
Purging configuration files for ksysguard-data (4:5.18.4.1-0ubuntu1) ...
Purging configuration files for ksysguardd (4:5.18.4.1-0ubuntu1) ...
Purging configuration files for libgtk2.0-0:amd64 (2.24.33-2ubuntu2) ...
Purging configuration files for libgtk2.0-common (2.24.33-2ubuntu2) ...
Purging configuration files for libkf5emoticons-data (5.92.0-0ubuntu1) ...
Purging configuration files for libkf5kmahjongglib-data (4:19.12.3-0ubuntu1) ...
Purging configuration files for libpython3.8-minimal:amd64 (3.8.10-0ubuntu1~20.04.7) ...
Purging configuration files for linux-modules-5.15.0-70-generic (5.15.0-70.77) ...
Purging configuration files for linux-modules-5.15.0-71-generic (5.15.0-71.78) ...
Purging configuration files for linux-modules-5.15.0-72-generic (5.15.0-72.79) ...
Purging configuration files for linux-modules-5.15.0-73-generic (5.15.0-73.80) ...
Purging configuration files for linux-modules-5.4.0-100-generic (5.4.0-100.113) ...
Purging configuration files for linux-modules-5.4.0-104-generic (5.4.0-104.118) ...
Purging configuration files for linux-modules-5.4.0-105-generic (5.4.0-105.119) ...
Purging configuration files for linux-modules-5.4.0-107-generic (5.4.0-107.121) ...
Purging configuration files for linux-modules-5.4.0-109-generic (5.4.0-109.123) ...
Purging configuration files for linux-modules-5.4.0-110-generic (5.4.0-110.124) ...
Purging configuration files for linux-modules-5.4.0-113-generic (5.4.0-113.127) ...
Purging configuration files for linux-modules-5.4.0-117-generic (5.4.0-117.132) ...
Purging configuration files for linux-modules-5.4.0-120-generic (5.4.0-120.136) ...
Purging configuration files for linux-modules-5.4.0-121-generic (5.4.0-121.137) ...
Purging configuration files for linux-modules-5.4.0-122-generic (5.4.0-122.138) ...
Purging configuration files for linux-modules-5.4.0-124-generic (5.4.0-124.140) ...
Purging configuration files for linux-modules-5.4.0-125-generic (5.4.0-125.141) ...
Purging configuration files for linux-modules-5.4.0-126-generic (5.4.0-126.142) ...
Purging configuration files for linux-modules-5.4.0-128-generic (5.4.0-128.144) ...
Purging configuration files for linux-modules-5.4.0-131-generic (5.4.0-131.147) ...
Purging configuration files for linux-modules-5.4.0-132-generic (5.4.0-132.148) ...
Purging configuration files for linux-modules-5.4.0-135-generic (5.4.0-135.152) ...
Purging configuration files for linux-modules-5.4.0-136-generic (5.4.0-136.153) ...
Purging configuration files for linux-modules-5.4.0-137-generic (5.4.0-137.154) ...
Purging configuration files for linux-modules-5.4.0-139-generic (5.4.0-139.156) ...
Purging configuration files for linux-modules-5.4.0-144-generic (5.4.0-144.161) ...
Purging configuration files for linux-modules-5.4.0-146-generic (5.4.0-146.163) ...
Purging configuration files for linux-modules-5.4.0-147-generic (5.4.0-147.164) ...
Purging configuration files for linux-modules-5.4.0-42-generic (5.4.0-42.46) ...
Purging configuration files for linux-modules-5.4.0-65-generic (5.4.0-65.73) ...
Purging configuration files for linux-modules-5.4.0-66-generic (5.4.0-66.74) ...
Purging configuration files for linux-modules-5.4.0-67-generic (5.4.0-67.75) ...
Purging configuration files for linux-modules-5.4.0-70-generic (5.4.0-70.78) ...
Purging configuration files for linux-modules-5.4.0-71-generic (5.4.0-71.79) ...
Purging configuration files for linux-modules-5.4.0-72-generic (5.4.0-72.80) ...
Purging configuration files for linux-modules-5.4.0-73-generic (5.4.0-73.82) ...
Purging configuration files for linux-modules-5.4.0-74-generic (5.4.0-74.83) ...
Purging configuration files for linux-modules-5.4.0-77-generic (5.4.0-77.86) ...
Purging configuration files for linux-modules-5.4.0-80-generic (5.4.0-80.90) ...
Purging configuration files for linux-modules-5.4.0-81-generic (5.4.0-81.91) ...
Purging configuration files for linux-modules-5.4.0-84-generic (5.4.0-84.94) ...
Purging configuration files for linux-modules-5.4.0-86-generic (5.4.0-86.97) ...
Purging configuration files for linux-modules-5.4.0-88-generic (5.4.0-88.99) ...
Purging configuration files for linux-modules-5.4.0-89-generic (5.4.0-89.100) ...
Purging configuration files for linux-modules-5.4.0-90-generic (5.4.0-90.101) ...
Purging configuration files for linux-modules-5.4.0-91-generic (5.4.0-91.102) ...
Purging configuration files for linux-modules-5.4.0-92-generic (5.4.0-92.103) ...
Purging configuration files for linux-modules-5.4.0-94-generic (5.4.0-94.106) ...
Purging configuration files for linux-modules-5.4.0-96-generic (5.4.0-96.109) ...
Purging configuration files for linux-modules-5.4.0-97-generic (5.4.0-97.110) ...
Purging configuration files for linux-modules-5.4.0-99-generic (5.4.0-99.112) ...
Purging configuration files for linux-modules-extra-5.15.0-70-generic (5.15.0-70.77) ...
Purging configuration files for linux-modules-extra-5.15.0-71-generic (5.15.0-71.78) ...
Purging configuration files for linux-modules-extra-5.15.0-72-generic (5.15.0-72.79) ...
Purging configuration files for linux-modules-extra-5.15.0-73-generic (5.15.0-73.80) ...
Purging configuration files for linux-modules-extra-5.4.0-100-generic (5.4.0-100.113) ...
Purging configuration files for linux-modules-extra-5.4.0-104-generic (5.4.0-104.118) ...
Purging configuration files for linux-modules-extra-5.4.0-105-generic (5.4.0-105.119) ...
Purging configuration files for linux-modules-extra-5.4.0-107-generic (5.4.0-107.121) ...
Purging configuration files for linux-modules-extra-5.4.0-109-generic (5.4.0-109.123) ...
Purging configuration files for linux-modules-extra-5.4.0-110-generic (5.4.0-110.124) ...
Purging configuration files for linux-modules-extra-5.4.0-113-generic (5.4.0-113.127) ...
Purging configuration files for linux-modules-extra-5.4.0-117-generic (5.4.0-117.132) ...
Purging configuration files for linux-modules-extra-5.4.0-120-generic (5.4.0-120.136) ...
Purging configuration files for linux-modules-extra-5.4.0-121-generic (5.4.0-121.137) ...
Purging configuration files for linux-modules-extra-5.4.0-122-generic (5.4.0-122.138) ...
Purging configuration files for linux-modules-extra-5.4.0-124-generic (5.4.0-124.140) ...
Purging configuration files for linux-modules-extra-5.4.0-125-generic (5.4.0-125.141) ...
Purging configuration files for linux-modules-extra-5.4.0-126-generic (5.4.0-126.142) ...
Purging configuration files for linux-modules-extra-5.4.0-128-generic (5.4.0-128.144) ...
Purging configuration files for linux-modules-extra-5.4.0-131-generic (5.4.0-131.147) ...
Purging configuration files for linux-modules-extra-5.4.0-132-generic (5.4.0-132.148) ...
Purging configuration files for linux-modules-extra-5.4.0-135-generic (5.4.0-135.152) ...
Purging configuration files for linux-modules-extra-5.4.0-136-generic (5.4.0-136.153) ...
Purging configuration files for linux-modules-extra-5.4.0-137-generic (5.4.0-137.154) ...
Purging configuration files for linux-modules-extra-5.4.0-139-generic (5.4.0-139.156) ...
Purging configuration files for linux-modules-extra-5.4.0-144-generic (5.4.0-144.161) ...
Purging configuration files for linux-modules-extra-5.4.0-146-generic (5.4.0-146.163) ...
Purging configuration files for linux-modules-extra-5.4.0-147-generic (5.4.0-147.164) ...
Purging configuration files for linux-modules-extra-5.4.0-42-generic (5.4.0-42.46) ...
Purging configuration files for linux-modules-extra-5.4.0-62-generic (5.4.0-62.70) ...
Purging configuration files for linux-modules-extra-5.4.0-64-generic (5.4.0-64.72) ...
Purging configuration files for linux-modules-extra-5.4.0-65-generic (5.4.0-65.73) ...
Purging configuration files for linux-modules-extra-5.4.0-66-generic (5.4.0-66.74) ...
Purging configuration files for linux-modules-extra-5.4.0-67-generic (5.4.0-67.75) ...
Purging configuration files for linux-modules-extra-5.4.0-70-generic (5.4.0-70.78) ...
Purging configuration files for linux-modules-extra-5.4.0-71-generic (5.4.0-71.79) ...
Purging configuration files for linux-modules-extra-5.4.0-72-generic (5.4.0-72.80) ...
Purging configuration files for linux-modules-extra-5.4.0-73-generic (5.4.0-73.82) ...
Purging configuration files for linux-modules-extra-5.4.0-74-generic (5.4.0-74.83) ...
Purging configuration files for linux-modules-extra-5.4.0-77-generic (5.4.0-77.86) ...
Purging configuration files for linux-modules-extra-5.4.0-80-generic (5.4.0-80.90) ...
Purging configuration files for linux-modules-extra-5.4.0-81-generic (5.4.0-81.91) ...
Purging configuration files for linux-modules-extra-5.4.0-84-generic (5.4.0-84.94) ...
Purging configuration files for linux-modules-extra-5.4.0-86-generic (5.4.0-86.97) ...
Purging configuration files for linux-modules-extra-5.4.0-88-generic (5.4.0-88.99) ...
Purging configuration files for linux-modules-extra-5.4.0-89-generic (5.4.0-89.100) ...
Purging configuration files for linux-modules-extra-5.4.0-90-generic (5.4.0-90.101) ...
Purging configuration files for linux-modules-extra-5.4.0-91-generic (5.4.0-91.102) ...
Purging configuration files for linux-modules-extra-5.4.0-92-generic (5.4.0-92.103) ...
Purging configuration files for linux-modules-extra-5.4.0-94-generic (5.4.0-94.106) ...
Purging configuration files for linux-modules-extra-5.4.0-96-generic (5.4.0-96.109) ...
Purging configuration files for linux-modules-extra-5.4.0-97-generic (5.4.0-97.110) ...
Purging configuration files for linux-modules-extra-5.4.0-99-generic (5.4.0-99.112) ...
Purging configuration files for mtools (4.0.33-1+really4.0.32-1build1) ...
Purging configuration files for mysql-common (5.8+1.0.8) ...
Purging configuration files for popularity-contest (1.71ubuntu3) ...
Purging configuration files for user-manager (4:5.18.4.1-0ubuntu1) ...
Purging configuration files for xul-ext-ubufox (3.4-0ubuntu1.17.10.1) ...

But it still looks quite full:

blabla:~$ sudo du -hd1 -x /
13M /root
8.0K /media
68K /snap
4.0K /cdrom
4.0K /mnt
256M /boot
16K /lost+found
du: cannot access '/tmp/.mount_jetbrazEc1eK': Permission denied
780K /tmp
11G /usr
4.0K /srv
12M /etc
12G /var
679M /opt
23G /

[kubicle]

kubicle I entered your command but I got an error apparently:
E: Unable to locate package xul-ext-ubufox

Yes, the command exits with that error and the residual configs aren't removed. It is a bit odd to see "unable to locate package" error when purging packages, though.

I'd first check the dpkg status of the package that throws the error:

dpkg --list | grep xul-ext-ubufox

to see if it also has residual-configs or is marked for installation (or possibly installation has been interrupted or something).

You can also try to only purge the conffiles of the linux-image packages to give you some space to work with:

sudo apt purge $(dpkg -l | grep linux-image | awk '/^rc/ {print $2}')

Optionally try another way of purging (using xargs, and dpkg instead of apt):

dpkg --list | awk '/^rc/ {print $2}' | sudo xargs dpkg --purge

[Robert24]

It looks the same to me:

blabla:~$ dpkg --list | grep linux-image
rc linux-image-5.15.0-70-generic 5.15.0-70.77 amd64 Signed kernel image generic
rc linux-image-5.15.0-71-generic 5.15.0-71.78 amd64 Signed kernel image generic
rc linux-image-5.15.0-72-generic 5.15.0-72.79 amd64 Signed kernel image generic
rc linux-image-5.15.0-73-generic 5.15.0-73.80 amd64 Signed kernel image generic
ii linux-image-5.15.0-75-generic 5.15.0-75.82 amd64 Signed kernel image generic
ii linux-image-5.15.0-76-generic 5.15.0-76.83 amd64 Signed kernel image generic
rc linux-image-5.4.0-100-generic 5.4.0-100.113 amd64 Signed kernel image generic
rc linux-image-5.4.0-104-generic 5.4.0-104.118 amd64 Signed kernel image generic
rc linux-image-5.4.0-105-generic 5.4.0-105.119 amd64 Signed kernel image generic
rc linux-image-5.4.0-107-generic 5.4.0-107.121 amd64 Signed kernel image generic
rc linux-image-5.4.0-109-generic 5.4.0-109.123 amd64 Signed kernel image generic
rc linux-image-5.4.0-110-generic 5.4.0-110.124 amd64 Signed kernel image generic
rc linux-image-5.4.0-113-generic 5.4.0-113.127 amd64 Signed kernel image generic
rc linux-image-5.4.0-117-generic 5.4.0-117.132 amd64 Signed kernel image generic
rc linux-image-5.4.0-120-generic 5.4.0-120.136 amd64 Signed kernel image generic
rc linux-image-5.4.0-121-generic 5.4.0-121.137 amd64 Signed kernel image generic
rc linux-image-5.4.0-122-generic 5.4.0-122.138 amd64 Signed kernel image generic
rc linux-image-5.4.0-124-generic 5.4.0-124.140 amd64 Signed kernel image generic
rc linux-image-5.4.0-125-generic 5.4.0-125.141 amd64 Signed kernel image generic
rc linux-image-5.4.0-126-generic 5.4.0-126.142 amd64 Signed kernel image generic
rc linux-image-5.4.0-128-generic 5.4.0-128.144 amd64 Signed kernel image generic
rc linux-image-5.4.0-131-generic 5.4.0-131.147 amd64 Signed kernel image generic
rc linux-image-5.4.0-132-generic 5.4.0-132.148 amd64 Signed kernel image generic
rc linux-image-5.4.0-135-generic 5.4.0-135.152 amd64 Signed kernel image generic
rc linux-image-5.4.0-136-generic 5.4.0-136.153 amd64 Signed kernel image generic
rc linux-image-5.4.0-137-generic 5.4.0-137.154 amd64 Signed kernel image generic
rc linux-image-5.4.0-139-generic 5.4.0-139.156 amd64 Signed kernel image generic
rc linux-image-5.4.0-144-generic 5.4.0-144.161 amd64 Signed kernel image generic
rc linux-image-5.4.0-147-generic 5.4.0-147.164 amd64 Signed kernel image generic
rc linux-image-5.4.0-42-generic 5.4.0-42.46 amd64 Signed kernel image generic
rc linux-image-5.4.0-62-generic 5.4.0-62.70 amd64 Signed kernel image generic
rc linux-image-5.4.0-64-generic 5.4.0-64.72 amd64 Signed kernel image generic
rc linux-image-5.4.0-65-generic 5.4.0-65.73 amd64 Signed kernel image generic
rc linux-image-5.4.0-66-generic 5.4.0-66.74 amd64 Signed kernel image generic
rc linux-image-5.4.0-67-generic 5.4.0-67.75 amd64 Signed kernel image generic
rc linux-image-5.4.0-70-generic 5.4.0-70.78 amd64 Signed kernel image generic
rc linux-image-5.4.0-71-generic 5.4.0-71.79 amd64 Signed kernel image generic
rc linux-image-5.4.0-72-generic 5.4.0-72.80 amd64 Signed kernel image generic
rc linux-image-5.4.0-73-generic 5.4.0-73.82 amd64 Signed kernel image generic
rc linux-image-5.4.0-74-generic 5.4.0-74.83 amd64 Signed kernel image generic
rc linux-image-5.4.0-77-generic 5.4.0-77.86 amd64 Signed kernel image generic
rc linux-image-5.4.0-80-generic 5.4.0-80.90 amd64 Signed kernel image generic
rc linux-image-5.4.0-81-generic 5.4.0-81.91 amd64 Signed kernel image generic
rc linux-image-5.4.0-84-generic 5.4.0-84.94 amd64 Signed kernel image generic
rc linux-image-5.4.0-86-generic 5.4.0-86.97 amd64 Signed kernel image generic
rc linux-image-5.4.0-88-generic 5.4.0-88.99 amd64 Signed kernel image generic
rc linux-image-5.4.0-89-generic 5.4.0-89.100 amd64 Signed kernel image generic
rc linux-image-5.4.0-90-generic 5.4.0-90.101 amd64 Signed kernel image generic
rc linux-image-5.4.0-91-generic 5.4.0-91.102 amd64 Signed kernel image generic
rc linux-image-5.4.0-92-generic 5.4.0-92.103 amd64 Signed kernel image generic
rc linux-image-5.4.0-94-generic 5.4.0-94.106 amd64 Signed kernel image generic
rc linux-image-5.4.0-96-generic 5.4.0-96.109 amd64 Signed kernel image generic
rc linux-image-5.4.0-97-generic 5.4.0-97.110 amd64 Signed kernel image generic
rc linux-image-5.4.0-99-generic 5.4.0-99.112 amd64 Signed kernel image generic
ii linux-image-generic

[Snowhog]

Rerun dpkg --list | grep linux-image

The resulting output should be WAY LESS and show one installed (ii) kernel.

[Robert24]

kubicle I entered your command but I got an error apparently:

(base) me:~$ sudo apt purge $(dpkg -l | awk '/^rc/ {print $2}')
[sudo] password for me:
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
E: Unable to locate package xul-ext-ubufox

[vanadiumboy]

Which use case? Gaming? Database server? And did you thoroughly test (and optimize) the swap behaviour of your system under heavy load?
How much physical memory do you have?
Do you use hibernation?

I guess it depends on what a person does.

I based it on past behavior but in my case, most of the past was with Windows.
All my PCs from 2015 and before, would use the swap file when I had many programs open or many image files open.
For example, when I had 2 GB RAM and I ran a certain game or left Firefox open, it would need the swap file.
Even with a system with 8 GB RAM, under certain circumstances, it would need another 1 GB.
With 16 GB RAM and more, my use case does not need a swap file.

Still, since HDD space is cheap, I just throw 50 GB to the swap space for Kubuntu.It will never complain that it is running low on swap space.