xkbset-gui: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/xkbset-gui - from package: xkbset

You may install the required package with command apt-get install {package}

Error in other languages:
xkbset-gui: bevel nie gevind nie
xkbset-gui: comandă negăsită
xkbset-gui: comando não encontrado
xkbset-gui: commande introuvable
xkbset-gui: command not found
xkbset-gui: käsku ei ole
xkbset-gui: không tìm thấy lệnh
xkbset-gui: komanda nerasta
xkbset-gui: Kommando nicht gefunden.
xkbset-gui: kommandot finns inte
xkbset-gui: komut yok
xkbset-gui: nie znaleziono polecenia
xkbset-gui: níor aimsíodh an t-ordú
xkbset-gui: no se encontró la orden
xkbset-gui: no s'ha trobat l'ordre
xkbset-gui: opdracht niet gevonden
xkbset-gui: parancs nem található
xkbset-gui: perintah tidak ditemukan
xkbset-gui: príkaz nenájdený
xkbset-gui: příkaz nenalezen
xkbset-gui: команда не найдена
xkbset-gui: командата не е открита
xkbset-gui: 命令找不到
xkbset-gui: コマンドが見つかりません