kaya-rekey: 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/kaya-rekey - from package: kaya

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

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