Ethercat installation from repositories - how to step by step

after

sudo apt install build-essential

unfortunatly I receive the same error mesage

folgenden Pakete haben unerfüllte Abhängigkeiten: ethercat-dkms : Hängt ab von: libtool ist aber nicht installierbar Hängt ab von: autoconf ist aber nicht installierbar Hängt ab von: autoconf-archive ist aber nicht installierbar Hängt ab von: automake ist aber nicht installierbar E: Probleme können nicht korrigiert werden, Sie haben zurückgehaltene defekte Pakete.

unfortunatly in german but basically libtool autoconf, ... can not be installed
I tried to install libtool individually: and I get the error message:

For the paket libtool there is no install candidate.

(my translation)

Is there any more information I can provide to narrow down the problem?

Strange. all packages are available in the Debian repositories (libtool,autoconf,autoconf-archive,automake)  packages.debian.org/search?suite=default...mes&keywords=libtool
Even stranger because iGh the ethercat master developer is a German company.. I wonder if its a language/locale issue? I can't help

Try


For me is says it can find libtool at 
 *** 2.5.4-4 500
        500 deb.debian.org/debian trixie/main amd64 Packages

But I'm on trixie so not identical.
 

hängt ab von means depends on
keine means none

unfortunatly i did do the sudo apt update already that would be to easy
just tried again and tried the build essentials afterwards it tells me it is already the newest version 12.9


should I do a reinstall with the english language? It seems od to me that this would depend on the language.

Is /etc/apt/sources.list broken?

how do i test this? (and fix if broken)

Show the content here it's not many lines.

That seems to be the problem
/etc/apt/sources.list contains only one line and i guess it wants the DVD i used to install it:
deb cdrom:[Debian GNU/Linux 12 _Bookworm_ - Official Snapshot amd64 LIVE/INSTALL Binary 20250127-13:30]/ bookworm contrib main non-free non-free-firmware

That won't work.
wiki.debian.org/SourcesList#Examples take the example for bookworm, I think you are on Debian 12.
You can add contrib to all lines, like "main contrib non-free" etc. Its says that on line 2 btw.