dvdunauthor: 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/dvdunauthor - from package: dvdauthor

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

On Debian possible default full paths are:

/usr/bin/dvdunauthor - from package: dvdauthor

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

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