gri909: 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/gri909 - from package: simh

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

Error in other languages:
gri909: bevel nie gevind nie
gri909: comandă negăsită
gri909: comando não encontrado
gri909: commande introuvable
gri909: command not found
gri909: käsku ei ole
gri909: không tìm thấy lệnh
gri909: komanda nerasta
gri909: Kommando nicht gefunden.
gri909: kommandot finns inte
gri909: komut yok
gri909: nie znaleziono polecenia
gri909: níor aimsíodh an t-ordú
gri909: no se encontró la orden
gri909: no s'ha trobat l'ordre
gri909: opdracht niet gevonden
gri909: parancs nem található
gri909: perintah tidak ditemukan
gri909: príkaz nenájdený
gri909: příkaz nenalezen
gri909: команда не найдена
gri909: командата не е открита
gri909: 命令找不到
gri909: コマンドが見つかりません