polyconvert: 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/polyconvert - from package: sumo

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

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