dateutils.ddiff: 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 Debian possible default full paths are:

/usr/bin/dateutils.ddiff - from package: dateutils

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

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