ola_trigger: 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_trigger - from package: ola

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

On Debian possible default full paths are:

/usr/bin/ola_trigger - from package: ola

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

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