nxproxy: 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/nxproxy - from package: nxproxy
/usr/lib64/nx/bin/nxproxy - from package: nxproxy
/opt/opennx/bin/nxproxy - from package: opennx

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

On Debian possible default full paths are:

/usr/bin/nxproxy - from package: nxproxy
/usr/lib/nx/bin/nxproxy - from package: nxproxy

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

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