argus: 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/argus - from package: argus-server

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

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