sudoku_generator: 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/sudoku_generator - from package: vdr-plugin-sudoku

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

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