nova-network: 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-network - from package: nova-network

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

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