dmg2img: 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/dmg2img - from package: dmg2img

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

On Debian possible default full paths are:

/usr/bin/dmg2img - from package: dmg2img

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

Error in other languages:
dmg2img: bevel nie gevind nie
dmg2img: comandă negăsită
dmg2img: comando não encontrado
dmg2img: commande introuvable
dmg2img: command not found
dmg2img: käsku ei ole
dmg2img: không tìm thấy lệnh
dmg2img: komanda nerasta
dmg2img: Kommando nicht gefunden.
dmg2img: kommandot finns inte
dmg2img: komut yok
dmg2img: nie znaleziono polecenia
dmg2img: níor aimsíodh an t-ordú
dmg2img: no se encontró la orden
dmg2img: no s'ha trobat l'ordre
dmg2img: opdracht niet gevonden
dmg2img: parancs nem található
dmg2img: perintah tidak ditemukan
dmg2img: príkaz nenájdený
dmg2img: příkaz nenalezen
dmg2img: команда не найдена
dmg2img: командата не е открита
dmg2img: 命令找不到
dmg2img: コマンドが見つかりません