dfbg: 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/dfbg - from package: directfb

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

On Debian possible default full paths are:

/usr/bin/dfbg - from package: libdirectfb-bin

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

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