mdns-scan: 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/mdns-scan - from package: mdns-scan

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

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