silvia_manager: 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 CentOS possible default full paths are:

/usr/bin/silvia_manager - from package: silvia

You may install the required package with command yum install {package}

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