intel_opregion_decode: 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 Debian possible default full paths are:

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

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

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