rs: 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/rs - from package: rs

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

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