gyotoy: command not found

Have You tried accessing the binary with the full path?

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/gyotoy - from package: yorick-gyoto

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