sgm_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/sgm_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/sgm_dd - from package: sg3-utils

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

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