installation - Unable to resolve Ruby error (missing psych)

Question

Whenever I run something with Ruby on my server, I get the following error:

/usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/yaml.rb:56:in `<top (required)>':
It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.

I installed Ruby using RVM onto my VPS.

I’ve tried installing the package libyaml as per instructed in other issues on Stack Overflow, to no avail.

I’m not sure what type of system my VPS is running, but it doesn’t have the apt-get command. It does have yum…

Answer 1

I have to disagree with @JunaidKirkire in that I think you are running CentOS or Redhat 5 which uses a a very old version of Ruby by default and I think using RVM is a much better way to go. I believe you will just need to compile libyaml from source with the following:

rvm pkg install libyaml

This will tell you the directory that it is compiling into, in my case, it is /Users/ehowe/.rvm/usr

You then need to recompile Ruby with the following option:

rvm reinstall 1.9.3 --with-libyaml-dir=$directory_that_rvm_installed_libyaml_to

So in my case, I would do:

rvm install 1.9.3 --with-libyaml-dir=/Users/ehowe/.rvm/usr

If you are running rvm as root, this will get installed into /usr/local/rvm/usr. If you are running it as a user, as is recommended, it would be /home/$user/.rvm/usr