I have already installed apache-tomcat  apache 6.0.33 and try to be install apache-tomcat7.0.47,After extracting the file trying to start Tomcat using startup. sh file showed below error,

#  ./bin/startup.sh
The BASEDIR environment variable is not defined
This environment variable is needed to run this program

Then I had  checked  $CATALINA_HOME  path, its does not point to version 6.0.33
-bash-3.2# echo $CATALINA_HOME

Let I changed the path to apache-tomcat-7.0.47 and Tried to start it Working fine without any issues,
# CATALINA_HOME=/usr/local/apache-tomcat-7.0.47

-bash-3.2# echo $CATALINA_HOME

Now,  start apache-tomcat server with same command,
-bash-3.2#  ./usr/local/apache-tomcat-7.0.47/bin/startup.sh
Using CATALINA_BASE:     /usr/local/apache-tomcat-7.0.47
Using CATALINA_HOME:   /usr/local/apache-tomcat-7.0.47
Using CATALINA_TMPDIR: /usr/local/apache-tomcat-7.0.47/temp
Using JRE_HOME:            /usr/java/jdk1.7.0
Using CLASSPATH:          /usr/local/apache-tomcat-7.0.47/bin/bootstrap.jar:/usr/local/apache-tomcat-7.0.47/bin/tomcat-juli.jar