root partition full

[Robert24]

Thank you all for your answers. Your support is very much appreciated.
I will try to reply to you one by one. (I started writing my reply but I realize that I won't have the time to finish it now because I have an appointment. I will come back and write a second message where I reply to all your other messages as soon as I can. Sorry for the delay, today I need to run everywhere)

Schwarzer Kater
I'm not sure what you meant about the formatting but I think that I removed all the tags in my previous posts and I will try to keep doing it.

Here is the output of sudo du -hd1 -x /:

blabla:~$ sudo du -hd1 -x /
[sudo] password for me:  
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
13M     /etc
12G     /var
679M    /opt
23G     /

I looked at the size of /var/lib and it takes 9.4G of space, 6.1G of which are allocated to /var/lib/snapd and 2.8G to /var/lib/docker.
Here is the detailed content of this last directory:

blabla:~$ sudo du -hd1 -x /var/lib/snapd
60K     /var/lib/snapd/cookie
1.1M    /var/lib/snapd/apparmor
2.3G    /var/lib/snapd/cache
4.0K    /var/lib/snapd/environment
4.0K    /var/lib/snapd/auto-import
284K    /var/lib/snapd/seccomp
8.0K    /var/lib/snapd/ssl
4.0K    /var/lib/snapd/void
4.0K    /var/lib/snapd/inhibit
3.9G    /var/lib/snapd/snaps
4.0K    /var/lib/snapd/hostfs
12K     /var/lib/snapd/dbus-1
68K     /var/lib/snapd/sequence
20K     /var/lib/snapd/lib
64K     /var/lib/snapd/mount
12K     /var/lib/snapd/device
40K     /var/lib/snapd/desktop
1.4M    /var/lib/snapd/assertions
4.0K    /var/lib/snapd/features
4.0K    /var/lib/snapd/firstboot
6.1G    /var/lib/snapd

Here are the output of the commands you suggested (I use the QUOTE tag because ther is a lot of bold).

sudo fdisk -l

blabla:~$ sudo fdisk -l
Disk /dev/loop0: 4 KiB, 4096 bytes, 8 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


Disk /dev/loop1: 118.23 MiB, 123973632 bytes, 242136 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


Disk /dev/loop2: 118.23 MiB, 123973632 bytes, 242136 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


Disk /dev/loop3: 55.64 MiB, 58339328 bytes, 113944 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


Disk /dev/loop4: 55.66 MiB, 58368000 bytes, 114000 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


Disk /dev/loop5: 245 MiB, 256905216 bytes, 501768 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


Disk /dev/loop6: 63.45 MiB, 66527232 bytes, 129936 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


Disk /dev/sda: 476.94 GiB, 512110190592 bytes, 1000215216 sectors
Disk model: SAMSUNG MZ7LN512
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: gpt
Disk identifier: DBAF1448-9672-4366-8996-CE771EE12CB2

Device Start End Sectors SizeType
/dev/sda1 2048 534527 532480 260M EFI System
/dev/sda2 534528 567295 32768 16M Microsoft reserved
/dev/sda3 567296 559597567 559030272 266.6G Microsoft basic data
/dev/sda4 998166528 1000214527 2048000 1000M Windows recovery environment
/dev/sda5 559597568 610797567 51200000 24.4G Linux filesystem
/dev/sda6 610797568 948389887 337592320 161G Linux filesystem
/dev/sda7 948389888 956778495 8388608 4G Linux swap
/dev/sda8 956778496 998166527 41388032 19.7G Linux filesystem

Partition table entries are not in disk order.


Disk /dev/loop9: 73.86 MiB, 77443072 bytes, 151256 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


Disk /dev/loop8: 73.85 MiB, 77438976 bytes, 151248 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


Disk /dev/loop10: 244.48 MiB, 256360448 bytes, 500704 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


Disk /dev/loop11: 164.82 MiB, 172830720 bytes, 337560 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


Disk /dev/loop12: 164.82 MiB, 172830720 bytes, 337560 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


Disk /dev/loop13: 349.69 MiB, 366673920 bytes, 716160 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


Disk /dev/loop14: 349.69 MiB, 366678016 bytes, 716168 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


Disk /dev/loop15: 63.45 MiB, 66531328 bytes, 129944 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


Disk /dev/loop16: 466.54 MiB, 489201664 bytes, 955472 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


Disk /dev/loop17: 81.26 MiB, 85209088 bytes, 166424 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


Disk /dev/loop18: 91.69 MiB, 96141312 bytes, 187776 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


Disk /dev/loop19: 76 KiB, 77824 bytes, 152 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


Disk /dev/loop20: 141.37 MiB, 148238336 bytes, 289528 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


Disk /dev/loop21: 180.46 MiB, 189227008 bytes, 369584 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


Disk /dev/loop22: 322.95 MiB, 338636800 bytes, 661400 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


Disk /dev/loop23: 347.02 MiB, 363876352 bytes, 710696 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


Disk /dev/loop24: 347.15 MiB, 364011520 bytes, 710960 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


Disk /dev/loop25: 485.52 MiB, 509100032 bytes, 994336 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

lsblk -e7

(base) blabla:~$ lsblk -e7
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sda 8:0 0 476.9G 0 disk
├─sda1 8:1 0 260M 0 part /boot/efi
├─sda2 8:2 0 16M 0 part
├─sda3 8:3 0 266.6G 0 part /media/me/Windows
├─sda4 8:4 0 1000M 0 part
├─sda5 8:5 0 24.4G 0 part /var/snap/firefox/common/host-hunspell
│ /
├─sda6 8:6 0 161G 0 part /home
├─sda7 8:7 0 4G 0 part [SWAP]
└─sda8 8:8 0 19.7G 0 part /media/me/backup

lsblk -f -e7

blabla:~$ lsblk -f -e7
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
sda
├─sda1
│ vfat FAT32 SYSTEM
│ D83C-5AC4 221M 14% /boot/efi
├─sda2
│
├─sda3
│ ntfs Windows
│ 96943F91943F733B 9.5G 96% /media/me/Windows
├─sda4
│ ntfs WinRE_DRV
│ 5C2C3FDF2C3FB33E
├─sda5
│ ext4 1.0 8e00456f-4fe4-4faf-b820-75e735c5f8db 303.4M 94% /var/snap/f
irefox/common/host-hunspell
│ /
├─sda6
│ ext4 1.0 c49de744-7baa-4273-980b-0ffcf1bd9808 80.5G 44% /home
├─sda7
│ swap 1 00072d64-416d-4566-8c59-0a3b469c6524 [SWAP]
└─sda8
ext4 1.0 backup
302f611e-26af-483d-aa59-81f160509a14 18.3G 0% /media/me/backup

oshunluvr I have to admit that I'm very ignorant when it comes to types of partitions. The closer I get to the physical machine the less idea I have about what's going on. I would actually love to understand these topics better. I'm trying to become a decent software engineer and I reduced my work percentage to have time to study a bit. Do you (or anyone else) have any recommendation regarding some resource which could provide me with a minimal background to understand these topics? I like reading books so if you have a reference on the topic, that would be great. Or maybe just some good blog because I'm not planning on becoming a specialist of the topic. I would just like to understand what you guys are talking about.
For the back-up, I made one yesterday on an external hard drive. I'm thinking of buying a second one just in case. I will aslo try to see if I can make a drop box account.
Concerning the back-up partition, I honestly don't remember where this comes from. As you realize I'm a bit lost so I tend to follow instructions like a monkey, which explains why I have empty partitions on my disk...
I have a bad memory of moving partitions on my disk (even if I have amazing memories of the support I received on this forum for solving this issue years ago), so I would prefer the safer option (2). Maybe next year, I'll reinstall the system with Kubuntu 24.04 and I'll try to make it as clean as possible.
About BTRFS and EXT4, I really have no clue what these represent and what are the difference. But I would love to learn.

[Robert24]

Snowhog I did indeed an upgrade from ubuntu 20.04 to 22.04 not so long ago. Here is the output of
ls -la /usr/src

(base)blabla:~$ ls -la /usr/src
total 24
drwxr-xr-x 6 root root 4096 Jun 29 09:10 .
drwxr-xr-x 14 root root 4096 Jul 31 2020 ..
drwxr-xr-x 25 root root 4096 Jun 19 20:50 linux-headers-5.15.0-75
drwxr-xr-x 7 root root 4096 Jun 19 20:50 linux-headers-5.15.0-75-generic
drwxr-xr-x 25 root root 4096 Jun 29 09:08 linux-headers-5.15.0-76
drwxr-xr-x 7 root root 4096 Jun 29 09:08 linux-headers-5.15.0-76-generic

kubicle here is the output of
dpkg --list | grep linux-image

(base) 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 5.15.0.76.74 amd64 Generic Linux kernel image

Thanks again for all your messages and support. It's very helpful.

PS: I see that my previous message where I tried to reply to most of your question, is marked as "Unapproved". I don't know if it's a temporary measure or if it's something else. I tried to use the QUOTE where there was too much bold or stuff like this in the terminal output, but maybe I missed something. Please, don't hesitate to correct me if I did something wrong.

[Snowhog]

It would probably be better to use something like:

dpkg --list | grep linux-image

Which should show installed kernel image packages, including ones that have not been completely removed (the ones that start with 'rc').

The OP’s output shows a lot of status ‘rc’ kernels.

[vanadiumboy]

Finally, I wouldn't be me if I didn't point out how using BTRFS instead of EXT4 would have avoided this problem. Instead of having a less than half empty /home and a full /, you would have one 180GB (sda5+sda6) partition at about 50% full and both the root OS and Home subvolumes sharing the free space. Kind of a difficult transition at this point, but maybe for a later install...

I don't understand.
You can have a single partition and format it as ext4.
Are you saying you can have multiple partitions, each one formated as BTRFS and it presents itself as a single partition?

[Snowhog]

No. What oshunluvr is saying is that with btrfs you can have a single 180GB partition instead of the two separate partitions you have now.

[kubicle]

The OP’s output shows a lot of status ‘rc’ kernels.

Yes, that's a lot of residual config-files for removed kernels...IMHO purging config-files definitely should be set as the default when removing packages.

One should be able to purge all residual configs for uninstalled packages with (for example):

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

How much space is freed depends on how many packages have been removed instead of purged

[vanadiumboy]

No. What oshunluvr is saying is that with btrfs you can have a single 180GB partition instead of the two separate partitions you have now.

Oh ok.
But you can do that with any filesystem format, of course.
25 GB as the OP has and even 180 GB is puny by today's standards. That's like a HDD from 2000 and 2005.

I would say, give it 1 TB.
If you are going to be installing a bunch games, each one 50 GB, then get yourself a minimum of 2 TB.

I just make a root partition of about 1 TB where everything is. I make a swap partition of 50 GB.
Eventually, I had to mount another 1 TB for the games.

Since Steam installs the games in my home folder, I mounted a 1 TB HDD disk to the Steam folder and copied all of it to that folder, which results in the files getting copied to HDD 2.
I think the folder is /home/john/.local/share/Steam

[Schwarzer Kater]

[…]
Schwarzer Kater
I'm not sure what you meant about the formatting but I think that I removed all the tags in my previous posts and I will try to keep doing it.
[…]

Thank you - I think Snowhog already was so kind to edit it.

You could also leave out the loop devices in the output of sudo fdisk -l (I did not take into account that you have some Snaps mounted by the system - and they are not needed for partitioning information of a drive).

Have you already done some "little things" like cleaning the APT cache, shrinking or removing the log files and purging all residual configs for uninstalled packages yet? This might not have that much of an effect, but it will not do any harm either and is worth a try with only 133 MB of free space left…

Moving the /swapfile to another partition and/or uninstalling and replacing the Firefox Snap will give you even more free space.

How much free space do you have now?


And slightly OT:

[…]
I make a swap partition of 50 GB.
[…]

There is at least some minimal context needed, because a 50 GB swap partition certainly is not best for everyone (but I do prefer swap partitions to swap files and to zram swap myself, for several reasons):

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?

[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.

[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

[Snowhog]

Rerun dpkg --list | grep linux-image

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

[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

[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]

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 /

[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?