ndpiReader: 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/ndpiReader - from package: libndpi-bin

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

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