monitorix: command not found

Have You tried accessing the binary with the full path?

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 CentOS possible default full paths are:

/usr/bin/monitorix - from package: monitorix

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