nash: 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/nash - from package: lrslib

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

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