poly.x: 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/poly.x - from package: palp

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

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