nproxy: 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 CentOS possible default full paths are:

/usr/bin/nproxy - from package: pdns-tools

You may install the required package with command yum install {package}

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