Download Macromedia Flex installer from the Macromedia website. This will require you register with Macromedia for a username and login.
http://www.macromedia.com/cfusion/tdrc/index.cfm?product=flex
Execute the installer file:
sh flex-15-linux.bin
Select your directory, while the default is /root/Macromedia/Flex I choose to place it in /opt/Flex
When you place a WAR file in your /usr/java/tomcat/webapps directory, Tomcat will automatically deploy that WAR on startup. This is a quick and easy way to deploy any application. Specifically with Flex, you can deploy your flex.war to create a basic Flex application, or rename flex.war to any other name to deploy your own application.
Move the flex.war file to the /usr/java/tomcat/webapps directory
mv /opt/Flex/flex.war /usr/java/tomcat/webapps/
Restart Tomcat and it will automatically deploy the flex.war file to the /usr/java/tomcat/webapps/flex directory
/etc/init.d/catalina restart
Since Tomcat will start on server start, so will Flex