For RHEL 6, you will need to enable EPEL repository, with a command like this:
sudo rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
Then install Ivy (this should work on Fedora too):
sudo yum install apache-ivy
Note: The Ivy client will download required files the first time it is run, which may take several minutes. It will show
resolving dependencies... while this is happening.
Download an Ivy binary distribution, extract Ivy's jar file somewhere, and set the environment variable
IVY_JAR to point to it.