ribbon: 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/ribbon - from package: raster3d

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

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