microcode_ctl: 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:

/sbin/microcode_ctl - from package: microcode_ctl

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

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