nova-xvpvncproxy: 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-xvpvncproxy - from package: nova-consoleproxy

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

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