argonaut-server: 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/sbin/argonaut-server - from package: argonaut-server

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

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