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I have installed a Ubuntu 18.04 with manual disk partitioning as simple as it gets (one primary partition with ext4 filesystem, mount point "/", reserved blocks 0%, bootable flag on, no swap!).

I have noticed now that there is active swap space anyway:

:~$ free -m|awk 'NR==1{print} /Swap/ {print}'
          total        used        free      shared  buff/cache   available
Swap:     397          0           397

And it's created as a file:

:~$ grep swap /etc/fstab
/swapfile    none    swap    sw    0    0

I could go ahead a simply turn off the swap space and delete the file as well as the fstab entry. But I would like to understand how to properly remove it from systemd as well. I can see a target defined for swap and I was wondering how to deactivate it and remove it from the list of targets before I eventually kill the swap file:

:~$ systemctl -t target |grep swap
swap.target            loaded active active Swap

Any ideas?

UPDATE

If the service is masked, it won't appear in the target list anymore and the fstab entry is ignored:

:~$ systemctl mask swap.target
Created symlink /etc/systemd/system/swap.target → /dev/null.
sre
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  • https://www.freedesktop.org/software/systemd/man/systemd.swap.html has all you need to know. and https://askubuntu.com/questions/816285/what-is-the-difference-between-systemctl-mask-and-systemctl-disable on how to mask or disable services – Rinzwind Aug 15 '18 at 07:56
  • Thanks! mask is indeed the right way (systemctl mask swap.target) – sre Aug 15 '18 at 08:16
  • Please note that swap.target is a special target that is only there for ordering, so other units can use After=swap.target to ensure they run after swap has been setup (if there is any swap to set up.) In other words, you should probably not mask swap.target, instead just remove any swap configuration from fstab. See documentation for swap units for more details. – filbranden Aug 16 '18 at 04:30
  • @filbranden Removing entries in fstab for swap are ignored, Ubuntu / Debian loads the swap anyway through systemctl. So fstab isn't the right suggestion. – Owl Jul 05 '22 at 01:14

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