rbash: 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:

/bin/rbash - from package: bash

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

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