dvbscan: 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/dvbscan - from package: dvb-apps

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

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