سلام دوست عزیز ممنون از جوابتون، دستور سما اجرا شد و خروجی آن هم این بوده است:

Loaded plugins: fastestmirror, protectbase
Loading mirror speeds from cached hostfile
epel/metalink | 14 kB 00:00
* atomic: www2.atomicorp.com
* base: centos-distro.cavecreek.net
* epel: mirrors.solfo.com
* extras: mirrors.kernel.org
* updates: linux.mirrors.es.net
atomic | 1.9 kB 00:00
base | 3.7 kB 00:00
extras | 3.4 kB 00:00
updates | 3.4 kB 00:00
0 packages excluded due to repository protections
Setting up Install Process
Package wget-1.12-1.8.el6.x86_64 already installed and latest version
Package gcc-4.4.7-3.el6.x86_64 already installed and latest version
Package gcc-c++-4.4.7-3.el6.x86_64 already installed and latest version
Package flex-2.5.35-8.el6.x86_64 already installed and latest version
Package bison-2.4.1-5.el6.x86_64 already installed and latest version
Nothing to do


لطفا کمک کنید.