Install and configure the X Windows Virtual Frame Buffer (Xvfb)
You install X Windows Virtual Frame Buffer (Xvfb) to enable graphs in Empirica Signal.
Prerequisites:
- Yum is installed and configured to use the appropriate configuration file.
- Your system can connect to the yum repositories.
Note: If Xvfb version 17.4-17.0.1.el6_9.1.x86_64 is installed or retrieved by yum, then either downgrade to 1.17.4-16.0.1.el6_9.1.x86_64, or obtain Xvfb version 1.17.4-17.0.2.el6 or later.
Perform these steps using the privileged user account on the application server.
- Determine whether Xvfb is installed:
- Execute the following command in a command shell:
$ which Xvfb
If a path to Xvfb appears, Xvfb is already installed. Alternatively, Xvfb is not installed.
- If Xvfb is already installed, skip to step 3.
- Execute the following command in a command shell:
- Install Xvfb:
- Enter the following command to initiate the installation:
$ sudo yum install Xvfb
A password prompt might appear.
- If a password prompt appears, enter the password for the privileged user account on the application server.
A confirmation prompt appears.
- Enter Y, and press Enter.
- Enter the following command to initiate the installation:
- Execute the following cp and chkconfig -add commands to enable Xvfb:
$ sudo su - root
# cp <INSTALL_DIR>/service/xvfb /etc/rc.d/init.d
# /sbin/chkconfig --add xvfb
where <INSTALL_DIR> is the Empirica Signal installation directory. For more information, see Unpack the installation files into the installation directory.
- Execute the chkconfig --list command to verify that the installation was successful, for example:
# /sbin/chkconfig --list xvfb
The following response appears:
xvfb 0:off 1:off 2:off 3:on 4:off 5:on 6:off
- Execute the start command to start Xvfb, for example:
# /etc/rc.d/init.d/xvfb start
The following response appears:
Starting X Virtual Frame Buffer
- Enter exit to terminate your session as the root user.