nbdswapd: 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/sbin/nbdswapd - from package: ltsp-server

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

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