ohhandler: 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/ohhandler - from package: openhpi32

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

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