#I just wanna share my experience when updating julia from 0.3.11 to 0.4.0.
#If you're using Ubuntu you can use:
sudo apt-get dist-upgrade julia
#It will bring the previous version be upgraded to the new version.
#But, the installed packages on the previous version won't be pulled up to the new version.
#If you're using IJulia, when you start your "jupyter notebook",
#your jupyter kernel won't detect the new version of julia,
#but still detects the previous one. Also, the previous one be a dead kernel.
#You've to install IJulia manually from
Pkg.add("IJulia")
#That's all.