ukopp: 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/ukopp - from package: ukopp

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

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