key: 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/key - from package: donkey

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