When and Why run alternatives --install java jar javac javaws on installing jdk in linux

Question

To install java in linux (I used CentOS, RHEL is same too), I used this command

rpm -Uvh /path/to/binary/jdk-7u55-linux-x64.rpm

and verified java

Answer 1

To get a different version of java JRE/JDK as default in your OS:

sudo alternatives --install /usr/bin/java java [path_to_java_bin] 1 

Example in my case was:

sudo alternatives --install /usr/bin/java java /usr/java/jdk1.7.0_80/bin/java 1 

Then run a config to select the alternative java version:

 sudo /usr/sbin/alternatives --config java

Choose 1,2 or the option you desire

Then check the changes by doing:

java -version