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')

Configure VLAN tagging via CLI

1. Create VLAN interface
# ip link add link eth4 name eth4.2030 type vlan id 2030

2. Assign IP
# ifconfig eth4.2030 11.0.20.1 netmask 255.255.240.0

3. Make sure new interface is enabled
# ifconfig eth4.2030 up

4. Check 
# ifconfig eth4.2030
eth4.2030 Link encap:Ethernet  HWaddr 90:E2:BA:6D:B5:95
          inet addr:11.0.20.1  Bcast:11.0.31.255  Mask:255.255.240.0
          inet6 addr: fe80::92e2:baff:fe6d:b595/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:10 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1046 (1.0 KiB)  TX bytes:468 (468.0 b)

5. Remove VLAN
# ip link delete eth4.2030

Sync Clock Automatically on CentOS

Got it from here.

1. Install
# yum install ntp ntpdate ntp-doc

2. Turn on service
# chkconfig ntpd on

3. Sync one time
# ntpdate pool.ntp.org

4. Configure ntpd
# vi /etc/ntp.conf
Add public servers
server 0.rhel.pool.ntp.org
server 1.rhel.pool.ntp.org
server 2.rhel.pool.ntp.org

5. Start the NTP server. The following will continuously adjusts system time from upstream NTP server. No need to run ntpdate:
# /etc/init.d/ntpd start

Install Ruby via RVM on CentOS 6.5

Got install from here.
RVM best practices here.
How to use RVM gemsets here.
How to use Bundler here.

1. Install pre-requisites
# yum groupinstall -y development

2. Install RVM
# curl -L get.rvm.io | bash -s stable

3. Create system environment for RVM
# source /etc/profile.d/rvm.sh

4. Install Ruby
# rvm reload
# rvm install 2.2.1

5. Check version of ruby installed
# ruby --version

6. To see all rubies installed
# rvm list rubies
rvm rubies
=* ruby-2.2.1 [ x86_64 ]
# => - current
# =* - current && default
#  * - default

7. To set a Ruby version as the default
# rvm use 2.2.1 --default
Using /usr/local/rvm/gems/ruby-2.2.1

8. Shortcut - create a new gemset along with a fresh .rvmrc in our project directory
# cd projects/dev/phoenix
# rvm --rvmrc --create use 2.2.1@phoenix
ruby-2.2.1 - #gemset created /usr/local/rvm/gems/ruby-2.2.1@phoenix
ruby-2.2.1 - #generating phoenix wrappers..........
Using /usr/local/rvm/gems/ruby-2.2.1 with gemset phoenix

9. To ignore rmvrc warnings ...
# rvm rvmrc warning ignore all.rvmrcs

10. Now when we cd to our project directory we get a confirmation which ruby-version and gemset we are using...
dev]# cd phoenix/
Using: /usr/local/rvm/gems/ruby-2.2.1@phoenix

11. Let's make use of bundler to make it easy to track and install the exact gems and versions for our project
# gem install bundler

12. Create a Gemfile
# bundle init
Writing new Gemfile to /root/projects/dev/phoenix/Gemfile

13. Add gems to Gemfile
# vi Gemfile
source "https://rubygems.org"
# 1. de facto XML/HTML parsing library
gem 'nokogiri'

14. Now, let's install all gems we listed in the Gemfile
# bundle install

To create and use gemsets the longer way:
a. Create gemset
# rvm gemset create my_proj

b. Use the gemset
# rvm gemset use my_proj

c. Install a gem
# gem install package_name

d. Wipe all gems installed
# rvm gemset empty my_proj

e. Delete the gemset
# rvm gemset delete my_proj

f. Check your current gemset
# rvm gemset name

Open HTTP port 80 on CentOS

Got from here.

1. Look at the current iptables
# iptables --line -vnL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
num   pkts bytes target     prot opt in     out     source               destination
1        0     0 ACCEPT     udp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           udp dpt:53
2        0     0 ACCEPT     tcp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           tcp dpt:53
3        0     0 ACCEPT     udp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           udp dpt:67
4        0     0 ACCEPT     tcp  --  virbr0 *       0.0.0.0/0            0.0.0.0/0           tcp dpt:67
5     195K  212M ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0           state RELATED,ESTABLISHED
6        3   252 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0
7       74  5440 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0
8       16   864 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0           state NEW tcp dpt:22
9     170K   39M REJECT     all  --  *      *       0.0.0.0/0            0.0.0.0/0           reject-with icmp-host-prohibited

2. Inject rule, as long as it's before the REJECT line
# iptables -I INPUT 5 -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT

3. Save
# service iptables save

4. Add httpd_t to the list of permissive domains (So we don't need to turn off selinux)
# yum install policycoreutils-python
# semanage permissive -a httpd_t

Perl specific installs for Centos 6.6

1. Enable RPMForge Repository

# wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm
# rpm -Uvh rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm
# rpm --import http://dag.wieers.com/rpm/packages/RPM-GPG-KEY.dag.txt

2. Install perl installs

MANUAL:
1. Dependency of Net::SSH::Perl
# wget http://download.opensuse.org/repositories/home:/csbuild:/Perl/CentOS_CentOS-6/x86_64/perl-Math-GMP-2.04-2.5.x86_64.rpm
# rpm -Uvh perl-Math-GMP-2.04-2.5.x86_64.rpm

2. Dependency of gnuplot for Chart::Graph::Gnuplot
# wget http://www.my-guides.net/en/images/stories/fedora12/msttcore-fonts-2.0-3.noarch.rpm
# rpm -Uvh msttcore-fonts-2.0-3.noarch.rpm

YUM:
# yum install perl-Math-BigInt-GMP
# yum install perl-Math-Pari
# yum install perl-Archive-Zip
# yum install perl-Chart
# yum install perl-DBI
# yum install perl-DBD-MySQL
# yum install perl-Data-Compare
# yum install perl-Date-Manip
# yum install perl-JSON
# yum install perl-Net-Telnet
# yum install perl-NetAddr-IP
# yum install perl-Statistics-Descriptive
# yum install perl-Text-Table
# yum install perl-XML-Simple
# yum install perl-XML-Writer
# yum install gnuplot

CPAN:
# cpan Data::Diff
# cpan HTML::TextToHTML
# cpan XML::SemanticDiff
# cpan Chart::Graph - this didn't install

Force installed:
cpan[1]> force install Net::Telnet::Brcd

Install and Configure MariaDB on CentOS 6

1. Go to repository generator, select the desired repository. In my case, I got this:

# MariaDB 5.5 CentOS repository list - created 2013-12-07 02:35 UTC
# http://mariadb.org/mariadb/repositories/
[mariadb]
name = MariaDB
baseurl = http://yum.mariadb.org/5.5/centos6-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1

2. Create a new repo, and put the generated text above.

$ sudo vi /etc/yum.repos.d/MariaDB.repo

3. Install

$ sudo yum install MariaDB-server MariaDB-client MariaDB-devel MariaDB-common

4. Start mysql

$ sudo /etc/init.d/mysql start
$ sudo /sbin/chkconfig mysql on

5. Autostart mysql
Find out the name of service’s script from /etc/init.d/ directory e.g. mysqld or httpd
Add it to chkconfig

$ sudo /sbin/chkconfig --add mysqld

Make sure it is in the chkconfig.

$ sudo /sbin/chkconfig --list mysqld

Set it to autostart

$ sudo /sbin/chkconfig mysqld on

6. Setup mysql Login as root:

[samdc@perfdb4 apps]$ mysql -u root

Set root password:

MariaDB [(none)]> set password for root@localhost=password('mypass');
MariaDB [(none)]> set password for root@'127.0.0.1'=password('mypass');
MariaDB [(none)]> set password for root@'machine.domain.com'=password('mypass');

Delete anonymous:

MariaDB [(none)]> delete from mysql.user where user='';

7. Create db and user: Create db:

MariaDB [(none)]> create database mydb;

Create user myuser with password mypass:

MariaDB [(none)]> grant all on mydb.* to 'mydb' identified by 'mypass';
MariaDB [(none)]> grant all on mydb.* to 'mydb'@'localhost' identified by 'mypass';

8. Show databases

MariaDB [(none)]> show databases;