sys: 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/sys - from package: openafs-client

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

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