I have tried to install the Xvfb on red-hat 6.5 using
yum -y install xorg-x11-server-Xvfb
but it is not installed and it is giving msg th
The xorg-x11-server-Xvfb
package is officially available from RedHat for RHEL 6 and RHEL 7 under the Optional channel (RHEL Workstation Optional, or RHEL Server Optional).
From the comments: To enable the optional repo: subscription-manager repos --enable rhel-7-server-optional-rpms
and then you can install the package with yum install xorg-x11-server-Xvfb