donkey: 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/donkey - from package: donkey

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