http://deb.devuan.org/devuan/pool/main/ … n1_all.deb
...
copy file "ceres" to /usr/share/debootstrap/scripts/ as "ceres-devuan"
make the soft links @chimaera @excalibur for "ceres-devuan"

Again, Chimaera works well this way. Excalibur failed.

EDIT: the reason I'm asking is because "merge_usr" is defined in the "functions" that come with the debootstrap installation, since excalibur.

Debian Bullseye host.
Debootstrap Chimaera works.
Debootstrap Excalibur failed   ("merge_usr: command not found")

2. what do all those mean? same use case or different use case? successful or failing?

2025-11-28 19:32:34 URL:http://deb.devuan.org/merged/pool/DEBIAN/main/v/vim/vim-tiny_9.1.1230-2_amd64.deb [775840/775840] -> "/loc_chroot/excalibur//var/cache/apt/archives/partial/vim-tiny_2%3a9
2025-11-28 19:32:35 URL:http://deb.debian.org/debian/pool/main/n/newt/whiptail_0.52.25-1_amd64.deb [24712/24712] -> "/loc_chroot/excalibur//var/cache/apt/archives/partial/whiptail_0.52.25-1_amd6
2025-11-28 19:32:36 URL:http://deb.debian.org/debian/pool/main/z/zlib/zlib1g_1.3.dfsg+really1.3.1-1+b1_amd64.deb [88892/88892] -> "//loc_chroot/excalibur//var/cache/apt/archives/partial/zlib1g_1%
amd64: ok
/usr/share/debootstrap/scripts/excalibur: line 26: [: -eq: unary operator expected
amd64: ok
/usr/share/debootstrap/scripts/excalibur: line 26: [: -eq: unary operator expected
/usr/share/debootstrap/scripts/excalibur: line 116: merge_usr: command not found

2
#sudo debootstrap  --no-merged-usr  --arch amd64 excalibur /loc_chroot/excalibur http://deb.devuan.org/merged/ excalibur

E: Unmerged /usr is not compatible with excalibur

3
http://deb.devuan.org/devuan/pool/main/ … n1_all.deb
no longer available

4.1
http://deb.devuan.org/packages/merged/d … ackages.gz
has no "merge_usr"

4.2
http://deb.devuan.org/packages/merged/d … ackages.gz

Package: base-files
Version: 13.8+deb13u2devuan1
Essential: yes
Installed-Size: 390
Maintainer: Devuan Developers <devuan-dev@lists.dyne.org>
Architecture: amd64
Replaces: base, dpkg (<= 1.15.0), miscutils
Provides: base, usr-is-merged

#sudo debootstrap  --include=base-files  --arch amd64 excalibur /loc_chroot/excalibur http://deb.devuan.org/merged/ excalibur

...
I: Extracting zlib1g...

/loc_chroot/excalibur/debootstrap/debootstrap.log

/usr/share/debootstrap/scripts/excalibur: line 116: merge_usr: command not found

(the same incomplete installation)

2
As I mention in my previous post - Chimaera first and Excalibur from inside Chimaera  - works.

Talking about debugging - Chimaera works and Excalibur is not. So, the issue not on the Debian side but Devuan,

It doesn't  work from Debian Bullseye.

If you're installing Devuan from Debian (or the other way around) I would recommend using the --foreign/--second-stage method. This has worked for me in the past, when the standard single-stage method didn't.

However, it's possible to debootstrap  Chimaera first
and then debootstrap Excalibur from inside chroot Chimaera.

No "--exclude" needed:
#debootstrap  --arch amd64 excalibur /loc_chroot/excalibur http://deb.devuan.org/merged/ excalibur

Works fine and the result can be moved back to the Debian host.

I used Debian debootstrap to install Chimaera and Excalibur in directories.
Chimaera works well.
However, Excalibur failed to finalize installation dispute the similar environment.

1 Chimaera
1.1
Download http://deb.devuan.org/devuan/pool/main/ … n1_all.deb

copy file "ceres" to /usr/share/debootstrap/scripts/ as "ceres-devuan"
make the soft links @chimaera @excalibur for "ceres-devuan"

1.2
#sudo debootstrap --include "bash,zsh,wpasupplicant,locales,grub2,wget,curl,dhcpcd5" --arch amd64 chimaera /chroot/chimaera http://deb.devuan.org/merged/ chimaera
...
Base system installed successfully.

Now I can run
sudo chroot /chroot/chimaera /bin/su -l

It works well.

2 Excalibur
The same soft links @chimaera @excalibur for "ceres-devuan".

#sudo debootstrap --include "bash,zsh,wpasupplicant,locales,grub2,wget,curl,dhcpcd5" --arch amd64 excalibur /chroot/excalibur http://deb.devuan.org/merged/ excalibur
...
I: Extracting util-linux...
I: Extracting zlib1g...

At this point it suddenly stop.
No errors, but no complete installation neither.

--
Best regards