ris_gateway: 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/ris_gateway - from package: ctn

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

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