hdup: 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/sbin/hdup - from package: hdup

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

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