isodump: 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/isodump - from package: genisoimage

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

On Debian possible default full paths are:

/usr/bin/isodump - from package: genisoimage

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

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