Centos: install jdk

#tar -xzf jdk-7u51-linux-x64.tar.gz -C /opt/

#ln -s /opt/jdk1.7.0_51/bin/java /sbin/java

#echo "export JAVA_HOME=/opt/jdk1.7.0_51" > /etc/profile.d/java_env.sh

#echo "export JRE_HOME=/opt/jdk1.7.0_51/jre" >> /etc/profile.d/java_env.sh

#echo "export CLASSPATH=.:\$JAVA_HOME/lib:\$JRE_HOME/lib:\$CLASSPATH" >> /etc/profile.d/java_env.sh
#echo "export PATH=.:\$JAVA_HOME/bin:\$JRE_HOME/bin:\$PATH" >> /etc/profile.d/java_env.sh

#chmod +x /etc/profile.d/java_env.sh

#source /etc/profile.d/java_env.sh

#java -version