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 `

        

Answer 1

Make sure your Redhat machine has a valid subscription:

# subscription-manager list 

+-------------------------------------------+
    Installed Product Status
+-------------------------------------------+
Product Name:   Red Hat Enterprise Linux Server
Product ID:     69
Version:        7.1
Arch:           x86_64
Status:         Subscribed
Status Details: 
Starts:         06/13/2014
Ends:           06/12/2015

Status must say "Subscribed". If not, then suffer through getting a login and maybe purchasing a subscription at https://access.redhat.com/management/consumers.

When that's done, run

# subscription-manager repos --enable rhel-7-server-optional-rpms

then libyaml-devel will install OK.

Answer 2

On a RHEL based distro such as CentOS 6.x you need to add another yum repository such as EPEL which contain the libyaml-devel package.

Keys for EPEL or download
RPM for EPEL

More info:

• CentOS - Additional Resources
• Fedora Project: EPEL Howto

Would also suggest the use of yum-plugin-priorities

Add EPEL Yum Repository

rpm --import http://dl.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-6
rpm -Kih http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

Install libyaml-devel via yum

yum -y install libyaml-devel

Packages

Dependencies Resolved

====================================================================================
 Package                       Arch         Version           Repository       Size
====================================================================================
Installing:
 libyaml-devel                 x86_64       0.1.3-1.el6       epel             84 k
Installing for dependencies:
 libyaml                       x86_64       0.1.3-1.el6       epel             52 k

Transaction Summary
====================================================================================
Install       2 Package(s)