This post is a quick tutorial on how you can easily manage & switch between different versions of libraries that you have configured in your machine with the help of symbolic links. I am currently working on Apache Spark based project & I have to download & configure not only spark but other libraries like hadoop, zeppelin & hive in my machine. These libraries are frequently released with major &minor updates.
The idea here is to keep all the different versions of a given library in one place & create symbolic link against the version you want to use. Later, use that symbolic link in other places like .bash_profile or in custom scripts. In my machine, I have created a root level bin folder & inside that I have library specific directories. E.g. :
~ bin ~ bin/sparks/ ~ bin/hdfs/ ~ bin/zeppelins/ ~ bin/hives/
Inside each of the library specific directory, I have the various version specific directory of that library. For e.g. inside ~/bin/sparks/, I have :
Dec 10 2016 spark-2.0.2-bin-hadoop2.7 Jan 29 2017 spark-2.0.0-bin-hadoop2.7 Feb 22 2017 spark-2.1.0-bin-hadoop2.7 Mar 2 2017 spark-1.6.1-bin-hadoop2.6 Sep 5 16:17 spark-2.2.0-bin-hadoop2.7
Next step is to create the symbolic link. I prefer to create symbolic links inside the ~/bin directory but outside any of the library specific directory. For e.g if I want to work with latest spark version, I will create symbolic link as :
➜ ln -snf ~/bin/sparks/spark-2.2.0-bin-hadoop2.7 ~/bin/spark
Once you have symbolic links in place, then you can easily switch it to point to another version e.g.
➜ ln -snf ~/bin/sparks/spark-2.0.2-bin-hadoop2.7 ~/bin/spark
Next, you can refer the symbolic link instead of actual library in places where you need the application reference. For e.g. I have the following _HOME_ variables configured in my .zshrc file :
export SPARK_HOME=/Users/pawan/bin/spark export PATH=$PATH:$SPARK_HOME/bin
This is it. With the help of symbolic link,s you can not only manage different versions of libraries, you can also seamlessly navigate across different versions of a given library.