sgp_dd: 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/sgp_dd - from package: sg3_utils

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

On Debian possible default full paths are:

/usr/bin/sgp_dd - from package: sg3-utils

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

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