intel_reg_write: 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/intel_reg_write - from package: intel-gpu-tools

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

On Debian possible default full paths are:

/usr/bin/intel_reg_write - from package: intel-gpu-tools

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

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