polygraph-pgl2eng: 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-pgl2eng - from package: polygraph

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

Error in other languages:
polygraph-pgl2eng: bevel nie gevind nie
polygraph-pgl2eng: comandă negăsită
polygraph-pgl2eng: comando não encontrado
polygraph-pgl2eng: commande introuvable
polygraph-pgl2eng: command not found
polygraph-pgl2eng: käsku ei ole
polygraph-pgl2eng: không tìm thấy lệnh
polygraph-pgl2eng: komanda nerasta
polygraph-pgl2eng: Kommando nicht gefunden.
polygraph-pgl2eng: kommandot finns inte
polygraph-pgl2eng: komut yok
polygraph-pgl2eng: nie znaleziono polecenia
polygraph-pgl2eng: níor aimsíodh an t-ordú
polygraph-pgl2eng: no se encontró la orden
polygraph-pgl2eng: no s'ha trobat l'ordre
polygraph-pgl2eng: opdracht niet gevonden
polygraph-pgl2eng: parancs nem található
polygraph-pgl2eng: perintah tidak ditemukan
polygraph-pgl2eng: príkaz nenájdený
polygraph-pgl2eng: příkaz nenalezen
polygraph-pgl2eng: команда не найдена
polygraph-pgl2eng: командата не е открита
polygraph-pgl2eng: 命令找不到
polygraph-pgl2eng: コマンドが見つかりません