cache-url: 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/share/diskimage-builder/elements/cache-url/bin/cache-url - from package: diskimage-builder

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

On Debian possible default full paths are:

/usr/share/diskimage-builder/elements/cache-url/bin/cache-url - from package: python-diskimage-builder

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

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