为什么我不能随yum安装最新版本的ruby？

Question

I am frustrated: I want to yum install ruby and install Ruby 2.4.1 or 2.3.0. Instead it seems that I have to use RVM or rbenv to get any version after 2.0.0 and both of those tools require some arduous process.

Why is this so complicated? Shouldn't I be able to install Ruby with a single yum command and use '/usr/bin/ruby' like I would '/usr/bin/java'?

Answer 1

Things change between Ruby versions. With the release of Ruby 2.4.0, many gems and applications needed to be updated in order to be compatible without breaking, including JSON, Rails, Nokogiri and others.

Now, with a OS distribution, people usually expect two things:

1. relative stability over its release cycle, so, things which worked yesterday continue to work tomorrow
2. that all shipped packages are compatible to each other.

If the CentOS maintainers were to upgrade their Ruby version mid-release, they would have to ensure that all other software they ship which depends on Ruby is also compatible with this new version, probably by also updating it. This leads to a maintenance nightmare since, often, these updates also change features which break the first point of requiring stability.

Because of that distributions usually ship a single version of Ruby (or Python or Perl) and only fix necessary bugs by backporting the fixes to their versions. Major updates are usually only done with a complete new OS release. How often this happens depends on the distribution you use. CentOS/RHEL tend to be very slow, Debian is so-so, Ubuntu has slower-to-update LTS releases and quicker-to-update regular releases.

In general, you trade stability for bleeding edge. And for their base OS, most people running servers tend to favor stability.

To use a newer version of Ruby for your own apps, you can still use rbenv, RVM, or any of the other Ruby installers. You can install these custom Ruby versions along the OS version and configure your own applications to use these versions.