/proc/ is not mounted, but required for successful operation of systemd-tmpfiles. Please mount /proc/. Alternatively, consider using the --root= or --image= switches.

[Mario Marietto]

Hello.

I'm trying to install Ubuntu 24.04 inside the Linuxulator (Linux
emulation Layer) of FreeBSD. Something changed on the 24.04 becauseI
was able to install the 23.10 even if I got the systemd error,but now
the installation freezes totally. Does anyone have the solution to be
able to complete the installation ?

......
57 upgraded, 62 newly installed, 43 to remove and 756 not upgraded.
100 not fully installed or removed.
Need to get 0 B/51.8 MB of archives.
After this operation, 84.9 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Extracting templates from packages: 100%
Preconfiguring packages ...
Setting up systemd (255.4-1ubuntu8.4) ...

/proc/ is not mounted, but required for successful operation of
systemd-tmpfiles. Please mount /proc/. Alternatively, consider using
the --root= or --image= switches.

Failed to take /etc/passwd lock: Invalid argument

dpkg: error processing package systemd (--configure):

 installed systemd package post-installation script subprocess
returned error exit status 1
Errors were encountered while processing:
 systemd

I don't understand the reason of that error,because I have mounted the
proc directory inside the fstab file of FreeBSD like this :

mount -t linprocfs linprocfs /compat/ubuntu2410/proc

I have also mounted the other partitions needed to use ubuntu 24.04 :

mount -t linsysfs linsysfs /compat/ubuntu2410/sys
mount -t devfs devfs /compat/ubuntu2410/dev
mount -t tmpfs tmpfs /compat/ubuntu2410/dev/shm
mount -t fdescfs fdescfs /compat/ubuntu2410/dev/fd
mount -t nullfs xxx /compat/ubuntu2410/tmp

I think that error is misleading. It's a false flag.

The full guide is located here :

https://forums.freebsd.org/threads/linuxulator-how-to-install-brave-linux-app-on-freebsd-13-0.78879/

He used Ubuntu focal,but I followed the same procedure when I tried to
install Ubuntu 24.04.

-- 
Mario.