nast: 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/nast - from package: nast

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

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