aragorn: 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/aragorn - from package: aragorn

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

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