nova-cells: 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/nova-cells - from package: nova-cells

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

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