问题
Is there any way, on Ubuntu 9.04, to install Ruby 1.8 as ruby1.8 (or get rid of it altogether) and have Ruby 1.9 be the default ruby?
回答1:
I'm not really sure, but maybe this can help:
update-alternatives --config ruby
... and here's the non-interactive, scriptable, way:
update-alternatives --set ruby /usr/bin/ruby1.9.1
You may find out about available alternatives and respective /usr/bin/... paths by doing:
update-alternatives --query ruby
回答2:
Martin - Take a look at the following link: http://ryanbigg.com/2010/12/ubuntu-ruby-rvm-rails-and-you/
This is where installation of ruby is heading for ubuntu servers. This should allow you to not only switch to a ruby version when needed, but also keep gems separated based on ruby versions, etc.
回答3:
You can completely remove Ruby 1.8 too with:
sudo apt-get remove libruby1.8 ruby1.8 ruby1.8-dev rubygems1.8
After that, you will only have Ruby 1.9 installed.
回答4:
sudo \curl -L https://get.rvm.io | bash -s stable --ruby --rails
will install an up-to-date version of ruby (and rails), and allow you to avoid brokenness of Ubuntu's RVM, see https://stackoverflow.com/a/9056395/497756.
If you go this route, get rid of Ubuntu-installed versions and associated packages like bundle.
Details here: https://rvm.io/rvm/install/
(Note: this is the TL;DR version of the post by henry74.)
回答5:
Try this:
sudo apt-get install ruby1.9.1 rubygems1.9.1
or try building from source. this worked for me on ubuntu 9.04 and after a restart 1.9 was the standard ruby
来源：https://stackoverflow.com/questions/1892877/how-do-i-make-ruby-1-9-the-default-ruby-on-ubuntu