opcontrol: 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/opcontrol - from package: oprofile

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

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