You are absolutely right.

I think I know one of the things papa did wrong, and wouldn't admit. He opened gslapt and manually edited the repos in there.
Yes it's true I manually modified the file containing the repositories. What for? I have already installed Archlinux on another disk and I followed the documentation of Mr ...

root[/]# cat /etc/slapt-get/slapt-getrc
root[/]# cat /etc/slapt-get/slapt-getrc
# Working directory for local storage/cache.
WORKINGDIR=/var/slapt-get

# Exclude package names and expressions.
# To exclude pre and beta packages, add this to the exclude:
# [0-9\_\.\-]{1}pre[0-9\-\.\-]{1}
EXCLUDE ...

I chose a French repository which is the closest.
Result of sudo slapt-get --update

bash-4.3$ sudo slapt-get --update
Mot de passe :
Récupération des données du paquet [http://download.salixos.org/x86_64/slackware-14.2/]…Dans le cache
Récupération de la liste des correctifs [http://download ...

I completely redid the Salix installation. I deleted my disk partitions. I downloaded the Salix Live64 Xfce 14.2.1 DVD ISO file (x86_64, 64-bit) then with xfburn I burned a dvd. For the installation of Salix I created the following partitions:

Boot Device Start End Sectors Size Id Type
/dev/sda1 ...

1. You didn't install salix in the first place
2. You broke everything after installation and you really tried to do it (and not mentioned here)

Seeing that your prompt doesn't even match a salix system, I'll guess its option 1. You installed Slackware, installed slapt-get on top of it, then made ...

Command results:

bash-4.3$ sudo slapt-get -i libxkbcommon
Mot de passe :
Lecture de la liste des paquets…Fait
Aucun paquet de la sorte : libxkbcommon
bash-4.3$

bash-4.3$ cat /etc/slapt-get/slapt-getrcclear
cat: /etc/slapt-get/slapt-getrcclear: Aucun fichier ou dossier de ce type

bash-4.3$ cat ...

Both commands display nothing.

bash-4.3$ slapt-get --search libxkbcommon
bash-4.3$ inxi -S
bash: inxi : commande introuvable
bash-4.3$

I tried again but without success. I do not find libxkbcommon.
bash-4.3$ opera
opera: error while loading shared libraries: libxkbcommon.so.0: cannot open shared object file: No such file or directory
bash-4.3$ sudo slapt-get -i libxkbcommon
Mot de passe :
Reading package list…Done
No such package ...

I uninstalled opera from sourcery. With gslapt I searched for libxkbcommon.so.0 . Gslapt can't find it!