intel_display_poller: 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_display_poller - from package: intel-gpu-tools

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

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