join-dctrl: 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/join-dctrl - from package: dctrl-tools

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

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