gyoto: 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/gyoto - from package: gyoto

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