nixadmin@localhost ~]$ rbenv install 2.2.2
Downloading ruby-2.2.2.tar.bz2...
-> https://cache.ruby-lang.org/pub/ruby/2.2/ruby-2.2.2.tar.bz2
Installing ruby-2.2.2...
mkdir: cannot create directory ‘/home/nixadmin/.rbenv/versions’: Permission denied

BUILD FAILED (Fedora 23 using ruby-build 20160111-25-g3b0714a)

Inspect or clean up the working tree at /tmp/ruby-build.20160122002237.1111
Results logged to /tmp/ruby-build.20160122002237.1111.log

Last 10 log lines:
/tmp/ruby-build.20160122002237.1111 ~
/tmp/ruby-build.20160122002237.1111/ruby-2.2.2 /tmp/ruby-build.20160122002237.1111 ~