dvbackup: 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/dvbackup - from package: dvbackup

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

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