Install Python 2.7 and Python 3.5 alongside Python 2.6 on CentOS 6.5

I got mostly from this post.

Install Python 2.7 and Python 3.5 alongside Python 2.6 on CentOS 6.5

1. Prep
# yum groupinstall "Development tools"
# yum install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel

2. Compile as shared library - add /usr/local/lib on /etc/ld.so.conf
# vi /etc/ld.so.conf
include ld.so.conf.d/*.conf
/usr/local/lib
# ldconfig

3.  Install python on  /usr/local
# Python 2.7.12:
wget http://python.org/ftp/python/2.7.12/Python-2.7.12.tar.xz
tar xf Python-2.7.12.tar.xz
cd Python-2.7.12
./configure --prefix=/usr/local --enable-unicode=ucs4 --enable-shared 
make && make altinstall

# Python 3.5.2:
wget http://python.org/ftp/python/3.5.2/Python-3.5.2.tar.xz
tar xf Python-3.5.2.tar.xz
cd Python-3.5.2
./configure --prefix=/usr/local --enable-shared
make && make altinstall

4. Run ldconfig again
# ldconfig

5. Install python virtualenv
# yum install python-virtualenv

6. Create virtualenv for python2.7
$ mkdir project_home
$ cd project_home
$ virtualenv -p /usr/local/bin/python2.7 .venv2.7

7. Create virtualenv for python3.5
$ mkdir project_home
$ cd project_home
$ pyvenv-3.5 .venv3.5
(this seems to work even though I get an error message:
Unable to symlink '/usr/local/bin/python3.5' to '/auto/home/delacs/python_projects_on_perf_utils/test_project/.venv3.5/bin/python3.5')