dfbtest_window: 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 CentOS possible default full paths are:

/usr/bin/dfbtest_window - from package: directfb

You may install the required package with command yum install {package}

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