easy using update alternatives
While it is still very annoying in Linux to switch between different environment like JDK6 and JDK7, even though this is much easier than in Windows.
update-alternatives gives us a solution.
switch between different environements
Any installed kit and environment by
apt-get will automatically registered in
update-alternatives, which is in the folder of
/etc/alternatives, you could see it has so many symbolic links, different links point to that
bin command in real.
The strategy above ensured the flexibility to switch between different software and environment, you just need to use
sudo update-alternatives --config <name>
sudo update-alternatives --set <name> <bin_path>
to specify and switch to a new environment.
--config is an interactive command hence is very user friendly, whilst
--set have no prompt as to make it feasible to write script.
install or append new command
sudo update-alternatives --install <link> <name> <path> <priority>
link is the path where your
$PATH will included in, like
name is the name registered in alternatives, where it shown in
path is the real command path where you can use this path to execute target command, like
priority will affect default choice of this command, you could browse others by
update-alternatives --config <name> to have a comparison. with higher value means higher priority.
sudo update-alternatives --install /usr/bin/javac java /usr/lib/jvm/java-8.0.5-oracle-amd64/jre/bin/java 1000