polygraph-pop-test: 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/polygraph-pop-test - from package: polygraph

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

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