omega: 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/omega - from package: texlive

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

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