xkeystone: 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/xkeystone - from package: x11-xserver-utils

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

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