dfbtest_sync: 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_sync - from package: directfb

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

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