ola_e131: 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/ola_e131 - from package: ola

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

On Debian possible default full paths are:

/usr/bin/ola_e131 - from package: ola

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

Error in other languages:
ola_e131: bevel nie gevind nie
ola_e131: comandă negăsită
ola_e131: comando não encontrado
ola_e131: commande introuvable
ola_e131: command not found
ola_e131: käsku ei ole
ola_e131: không tìm thấy lệnh
ola_e131: komanda nerasta
ola_e131: Kommando nicht gefunden.
ola_e131: kommandot finns inte
ola_e131: komut yok
ola_e131: nie znaleziono polecenia
ola_e131: níor aimsíodh an t-ordú
ola_e131: no se encontró la orden
ola_e131: no s'ha trobat l'ordre
ola_e131: opdracht niet gevonden
ola_e131: parancs nem található
ola_e131: perintah tidak ditemukan
ola_e131: príkaz nenájdený
ola_e131: příkaz nenalezen
ola_e131: команда не найдена
ola_e131: командата не е открита
ola_e131: 命令找不到
ola_e131: コマンドが見つかりません