hd: 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/hd - from package: bsdmainutils

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

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