nmbscan: 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/nmbscan - from package: nmbscan

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

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