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Quick swap JDK versions (aliases) in Ubuntu



THE ALIAS COMMAND


The alias command makes it possible to launch any command or group of commands (inclusive of any options, arguments and redirection) by entering a pre-set string (i.e., sequence of characters).

CREATING ALIASES

The general syntax for the alias command varies somewhat according to the shell. In the case of the bash shell it is
alias [-p] [name="value"]

Aliases can be created in the .bashrc file in Ubuntu home directory. But without manipulating the .bashrc , it is the best practice to create a new file .bash_aliases in the home directory.

The .bashrc is a hidden file and if you don't see a file like this in home directory , press ctrl+h to unhide all the hidden files and folders. These are hidden because they are not to be edited. But in our case we need to edit these a little bit but carefully.

After creating the .bash_aliases open the .bashrc file in the home directory and check if the bellow code snippet is in the file.


If you do not see the code snippet inside the .bashrc, then you need to manually insert it there. But be careful when manipulating the .bashrc file because if it is done wrong you might get a boot loop error when you login next time.

If the code is available in the .bashrc, then open the .bash_aliases file and add the bellow code snippet into it.


JAVA_HOME path should point the JDK installed location. In my case the jdk binaries are extracted into my home directory.

If you do not know how to install JDK using binary distributions, please refer to my article on JDK installation using Binary distribution in Ubuntu. 

After the aliases are created, save the .bash_aliases file and enter the bellow command in terminal. You need to be in home directory to use the bellow command. That is because the .bash_aliases file is in home directory.


Then you can try changing the jdk version by typing just java7 or java8 in terminal. After entering the above commands, you can double check if the jdk versions are changed according to aliases by entering the bellow command in terminal.




That is the end of this article  and hope you learned something from this.



" - Chathumina Vimukthi"
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