tech.notes: 2015

12.03.2015

tmux Terminal Multiplexer

Good tutorial from here and here.

Managing tmux sessions:
$ tmux      # start tmux server
$ tmux at   # attach running sessions to a terminal
$ tmux ls   # list running tmux sessions
$ exit      # close tmux session

Sharing sessions between terminals:
$ tmux new -s session_name # make new named session
$ tmux at -t session_name  # attach to exist session (allowing shared sessions)
$ tmux kill-session -t session_name  # kill named session

Commands (used within a running tmux session):

NOTE: All commands need to be prefixed with the action key.
      By default, this is CTRL-b

 c  - create new window
n/p - move to next/previous window
0-9 - move to window number 0-9
 f  - find window by name
 w  - menu with all windows
 &  - kill current window
 ,  - rename window

 %  - split window, adding a vertical pane to the right
 "  - split window, adding an horizontal pane below
←/→ - move focus to left/right pane
↑/↓ - move focus to upper/lower pane

 !  - Break current pane into new window
 x  - Kill the current pane.
 z  - toggle maximize the current pane.
 d  - detach the current client

 [  - enter copy mode (then use emacs select/yank keys)
      * press CTRL-SPACE or CTRL-@ to start selecting text
      * move cursor to end of desired text
      * press ALT-w to copy selected text

 ]  - paste copied text

 ?  - show tmux key bindings

11.08.2015

Install Go and Setup Vim as IDE

1. Install Go - http://www.hostingadvice.com/how-to/install-golang-on-ubuntu/
2. Configure Vim as IDE for Go - http://farazdagi.com/blog/2015/vim-as-golang-ide/
3. Docker image of Vim configured with Go - https://hub.docker.com/r/mbrt/golang-vim-dev/

Setup Notes:
When installing vim-go-ide while in corporate firewall, do a clone in this fashion...
git clone https://github.com/farazdagi/vim-go-ide.git ~/.vim_go_runtime

Additional configurations:
$ vim ~/.bashrc
gvm use go1.5.1
alias vimgo='vim -u ~/.vimrc.go'

$ vim ~/.vimrc.go
set t_Co=256

Using the Docker image (what I prefer):
$ cd your/go/workspace
$ docker run --rm -tiv `pwd`:/go mbrt/golang-vim-dev

8.13.2015

How to Create and Use SSL Certificates

From this post.

1. ~]$ mkdir CA
2. ~]$ cd CA
3. CA]$ mkdir newcerts private
4. CA]$ echo '01' >serial
5. CA]$ touch index.txt

Create a Root Certificate
6. CA]$ vi openssl.cnf
#
# OpenSSL configuration file.
#

# Establish working directory.

dir         = .

[ ca ]
default_ca      = CA_default

[ CA_default ]
serial          = $dir/serial
database        = $dir/index.txt
new_certs_dir   = $dir/newcerts
certificate     = $dir/cacert.pem
private_key     = $dir/private/cakey.pem
default_days    = 365 
default_md      = md5 
preserve        = no
email_in_dn     = no
nameopt         = default_ca
certopt         = default_ca
policy          = policy_match

[ policy_match ]
countryName     = match
stateOrProvinceName = match
organizationName    = match
organizationalUnitName  = optional
commonName      = supplied
emailAddress        = optional

[ req ]
default_bits        = 1024          # Size of keys
default_keyfile     = key.pem       # name of generated keys
default_md      = md5           # message digest algorithm
string_mask     = nombstr       # permitted characters
distinguished_name  = req_distinguished_name
req_extensions      = v3_req

[ req_distinguished_name ]
# Variable name       Prompt string
#----------------------     ----------------------------------
0.organizationName    = Organization Name (company)
organizationalUnitName    = Organizational Unit Name (department, division)
emailAddress      = Email Address
emailAddress_max  = 40
localityName      = Locality Name (city, district)
stateOrProvinceName   = State or Province Name (full name)
countryName       = Country Name (2 letter code)
countryName_min       = 2
countryName_max       = 2
commonName        = Common Name (hostname, IP, or your name)
commonName_max        = 64

# Default values for the above, for consistency and less typing.
# Variable name             Value
#------------------------------     ------------------------------
0.organizationName_default    = The Sample Company
localityName_default      = Metropolis
stateOrProvinceName_default   = New York
countryName_default       = US

[ v3_ca ]
basicConstraints  = CA:TRUE
subjectKeyIdentifier  = hash
authorityKeyIdentifier    = keyid:always,issuer:always

[ v3_req ]
basicConstraints    = CA:FALSE
subjectKeyIdentifier    = hash


7. CA]$ openssl req -new -x509 -extensions v3_ca -keyout private/cakey.pem -out cacert.pem -days 3650 -config ./openssl.cnf 
Generating a 1024 bit RSA private key
....................++++++
................++++++
writing new private key to 'private/cakey.pem'
Enter PEM pass phrase:demo
Verifying - Enter PEM pass phrase:demo
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Organization Name (company) [The Sample Company]:My Company
Organizational Unit Name (department, division) []:CA Division
Email Address []:ca@sample.com
Locality Name (city, district) [Metropolis]:Santa Clara
State or Province Name (full name) [New York]:California
Country Name (2 letter code) [US]:  
Common Name (hostname, IP, or your name) []:TSC Root CA

Create a Certificate Signing Request
8. CA]$ openssl req -new -nodes -out req.pem -config ./openssl.cnf
Generating a 1024 bit RSA private key
...++++++
.....................++++++
writing new private key to 'key.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Organization Name (company) [The Sample Company]:My Company
Organizational Unit Name (department, division) []:Web Server
Email Address []:ca@test.com
Locality Name (city, district) [Metropolis]:Santa Clara
State or Province Name (full name) [New York]:California
Country Name (2 letter code) [US]:US
Common Name (hostname, IP, or your name) []:hostname.domain.com

Sign a Certificate
9. CA]$ openssl ca -out cert.pem -config ./openssl.cnf -infiles req.pem
Using configuration from ./openssl.cnf
Enter pass phrase for ./private/cakey.pem:demo
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
organizationName      :PRINTABLE:'My Company'
organizationalUnitName:PRINTABLE:'Web Server'
localityName          :PRINTABLE:'Santa Clara'
stateOrProvinceName   :PRINTABLE:'California'
countryName           :PRINTABLE:'US'
commonName            :PRINTABLE:'hostname.domain.com'
Certificate is to be certified until Aug 12 18:22:03 2016 GMT (365 days)
Sign the certificate? [y/n]:y
1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated

10. CA]$ cat key.pem cert.pem >key-cert.pem
11. CA]$ ls *.pem
cacert.pem  cert.pem  key-cert.pem  key.pem  req.pem

Deploy Certificate
12. Copy the appropriate files, usually cert.pem and key.pem to the location where the certificates will be used as specified by the application.

8.12.2015

Rails configure Webrick to use SSL

Came from this post. Change bin/rails to be...

To generate certificates, follow this post.

#!/usr/bin/env ruby

require 'rails/commands/server'
require 'rack'
require 'webrick'
require 'webrick/https'

if ENV['SSL'] == "true"
  module Rails
      class Server < ::Rack::Server
          def default_options
              super.merge({
                  :Port => 3001,
                  :environment => (ENV['RAILS_ENV'] || "development").dup,
                  :daemonize => false,
                  :debugger => false,
                  :pid => File.expand_path("tmp/pids/server.pid"),
                  :config => File.expand_path("config.ru"),
                  :SSLEnable => true,
                  :SSLVerifyClient => OpenSSL::SSL::VERIFY_NONE,
                  :SSLPrivateKey => OpenSSL::PKey::RSA.new(
                                   File.open("certs/key.pem").read),
                  :SSLCertificate => OpenSSL::X509::Certificate.new(
                                   File.open("certs/cert.pem").read),
                  :SSLCertName => [["CN", WEBrick::Utils::getservername]],
              })
          end
      end
  end
end

APP_PATH = File.expand_path('../../config/application',  __FILE__)
require_relative '../config/boot'
require 'rails/commands'

For self-signed certificates as outlined here.

#!/usr/bin/env ruby

require 'rails/commands/server'
require 'rack'
require 'webrick'
require 'webrick/https'

if ENV['SSL'] == "true"
  module Rails
      class Server < ::Rack::Server
          def default_options
              super.merge({
                  :Port => 3001,
                  :environment => (ENV['RAILS_ENV'] || "development").dup,
                  :daemonize => false,
                  :debugger => false,
                  :pid => File.expand_path("tmp/pids/server.pid"),
                  :config => File.expand_path("config.ru"),
                  :SSLEnable => true,
                  :SSLCertName => [["CN", WEBrick::Utils::getservername]],
              })
          end
      end
  end
end

APP_PATH = File.expand_path('../../config/application',  __FILE__)
require_relative '../config/boot'
require 'rails/commands'

Then run server as...

$ SSL=true rails s

A Simple Ruby DSL

It's very easy to create a new language with ruby, here's a simple DSL

class SleepActivity

  def initialize(name)
    @name = name
  end

  def start(&block)
    sleep 1
    puts "#{@name} goes to bed"
    instance_eval &block if block_given?
  end

  def slumber(&block)
    sleep 1
    puts "#{@name} is starting to sleep"
    instance_eval &block if block_given?
  end

  def cycle(period, &block)
    sleep 1
    period.times do |time|
      puts "Sleep cycle #{time + 1}:"
      instance_eval &block if block_given?
    end
  end

  def awake(duration)
    sleep 1
    puts "Still awake for #{duration} minutes"
  end

  def light_sleep(duration)
    sleep 1
    puts "Sleeping lightly for #{duration} minutes"
  end

  def deep_sleep(duration)
    sleep 1
    puts "Sleeping deeply for #{duration} minutes"
  end

  def rem(duration)
    sleep 1
    puts "REM for #{duration} minutes"
  end

end

if $PROGRAM_NAME == __FILE__
  sleep_activity = SleepActivity.new("Sam")
  sleep_activity.start do
    awake 5
    slumber do
      cycle 5 do
        light_sleep 20
        deep_sleep 60
        rem 10
      end
    end
  end
end

Here's the output

samdc@mango:~/dev/ruby/projects/dsl$ ruby dsl_interpreter.rb 
Sam goes to bed
Still awake for 5 minutes
Sam is starting to sleep
Sleep cycle 1:
Sleeping lightly for 20 minutes
Sleeping deeply for 60 minutes
REM for 10 minutes
Sleep cycle 2:
Sleeping lightly for 20 minutes
Sleeping deeply for 60 minutes
REM for 10 minutes
Sleep cycle 3:
Sleeping lightly for 20 minutes
Sleeping deeply for 60 minutes
REM for 10 minutes
Sleep cycle 4:
Sleeping lightly for 20 minutes
Sleeping deeply for 60 minutes
REM for 10 minutes
Sleep cycle 5:
Sleeping lightly for 20 minutes
Sleeping deeply for 60 minutes
REM for 10 minutes

7.21.2015

Bash Cheat Sheet

1. Run a script with no output and in the background
$ ./my_script.sh > /dev/null 2>&1 &

2.  Run a script with no output and in the background and see the pid
$ ./my_script.sh > /dev/null 2>&1 & echo $!

3. Template script that loops thru and writes to a file
#!/bin/bash

# $1 - number of minutes
# $2 - task id
COUNTER=$(($1*60/5))
TOTAL=$COUNTER
echo Perfload will run for $1 minutes
echo "Perfload will run for $1 minutes" > /tmp/$2.log
until [  $COUNTER -eq 0 ]; do
    echo The counter is $COUNTER
    PROGRESS=$(echo "scale=2;($TOTAL - $COUNTER)*100/$TOTAL" | bc -l)
    echo "Perfload RUNNING $PROGRESS %" >> /tmp/$2.log
    let COUNTER-=1
    sleep 5
done
echo "Perfload SUCCESS" >> /tmp/$2.log

7.14.2015

Cisco Switch Cheat Sheet


sho lldp neighbors
sho cdp ne

switch-name# show mac address-table | i 0060.165c.f83e
* 2016     0060.165c.f83e    dynamic     ~~~      F    F  Eth1/22

switch-name# sho int description | grep 'yogi34 eth4b'
Eth8/19       eth    10G     yogi34 eth4b 90E2BA068BB1

switch-name# show interface ethernet 2/27 description
-------------------------------------------------------------------------------
Port          Type   Speed   Description
-------------------------------------------------------------------------------
Eth2/27       eth    10G     artemis59-eth3b 0060.1645.505a

switch-name(config)# config
switch-name(config)# int e8/19
switch-name(config-if)# inherit port-profile Apposite
switch-name(config-if)# exit
switch-name(config)# exit
switch-name# copy run startup-config

switch-name# show interface ethernet 1/28 switchport

# If missing VLANs, can set using...
switch-name(config-if)# switchport trunk allow vlan 2016,2030-2049

5.15.2015

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

4.29.2015

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

3.12.2015

Ansible for Configuration Management and IT automation

Wow, Ansible is a great tool for configuration management and IT automation. I got this reference from here and here.

1. Install ansible on your workstation (machine which will be the controller)
$ sudo yum install ansible
$ ansible --version

2. Create env variable
$ export ANSIBLE_HOSTS=~/ansible/ansible_hosts

3. Create hosts file
$ echo -e "perf-c690\nperf-c691" > ~/ansible/ansible_hosts

4. Do a quick ping
$ ansible all -m ping --ask-pass

5. Now, let's create ssh keys
(Should typically run using your own user account, have used root here for convenience) 
# ssh-keygen -t rsa

6. Copy public key to the remote machines
$ ansible all -m copy -a "src=/root/.ssh/id_rsa.pub dest=/tmp/id_rsa.pub" --ask-pass -c paramiko

Warning: error message: "Aborting, target uses selinux but python bindings (libselinux-python) aren't installed!"
Which means we need to install libselinux-python on the remote machine prior to copying the files there. We can use ansible to do that for us.

Install libselinux-python on remote machines
$ ansible all -m yum -a "name=libselinux-python state=latest" -u root --ask-pass -c paramiko

Now we can go back to copying the public key

7. Let's add the public key to the remote machines
$ ansible all -m shell -a "cat /tmp/id_rsa.pub >> /root/.ssh/authorized_keys" --ask-pass -c paramiko

8. Test if we actually don't need any password
$ ansible all -m shell -a "hostname"

9. Now we can do or install whatever on the remote machines, let's try installing expect
$ ansible all -m yum -a "name=expect state=latest" -u root

10. We can remotely reboot all machines at once
$ ansible all -a "/sbin/reboot" -u root

3.10.2015

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

2.19.2015

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

2.13.2015

Install different versions of Perl on Linux using Perlbrew

Got from here and here. What is perlbrew.

1. Install perfbrew
$ curl -kL http://install.perlbrew.pl | bash

2. Modify .bashrc and add:
source ~/perl5/perlbrew/etc/bashrc

3. Initialize
$ perlbrew init

4. Select mirror
$ perlbrew mirror

5. See what's available
$ perlbrew available
  perl-5.20.1
  perl-5.18.4
  perl-5.16.3
  perl-5.14.4

6. Install perls
$ perlbrew install perl-5.20.1  # did not work for Centos 6.5
$ perlbrew --notest install perl-5.20.1

7. See what were installed
$ perlbrew list

8. Swith to an installation and set it as default
$ perlbrew switch perl-5.20.1

9. Temporarily use another version only in current shell.
$ perlbrew use perl-5.20.1
$ perl -v

10. Or turn it off completely. Useful when you messed up too deep. Or want to go back to the system Perl.
$ perlbrew off

11. Use 'switch' command to turn it back on.
$ perlbrew switch perl-5.20.1

12. Exec something with all perlbrew-ed perls
$ perlbrew exec -- perl -E 'say $]'

13. Install cpanm
$ perlbrew install-cpanm

14. Install cpan modules
$ cpanm install File::Copy::Recursive XML::Simple etc

2.07.2015

Ruby Notes

While reading RubyMonk tutorials

1. Truthiness of objects in Ruby
Only objects false and nil equates to false. Every other object like say 1, 0, "" are all evaluated to be true.

2. Use break in infinite loops

loop do
  monk.meditate
  break if monk.nirvana?
end

3. Append to an array, use << operator

[1, 2, 3, 4, 5] << 'woot'
[1, 2, 3, 4, 5, "woot"]

4. Filter elements of an array, use 'select'

names = ['rock', 'paper', 'scissors', 'lizard', 'spock']
names.select { |word| word.length > 5 }

5. Delete elements of an array, use 'delete_if'

[1,2,3,4,5,6,7,8,9].delete_if { |i| i % 2 == 0 }

6. Methods are themselves objects, and responds using 'call'

next_method_object = 1.method("next")
puts next_method_object.call

7. Beware of shallow object copies, to do a deep copy use Marshal

new_job = Marshal.load(Marshal.dump(job))

8. Use heredoc for convenient multiline strings. The dash ignores spaces before placeholder. The gsub takes care of removing spaces at beginning of each line.

def long_message
  puts <<-EOT.gsub(/^\s*/, '')
    Here goes a very long message...
    Sincerely,
    Dr. Foobear
  EOT
end

7. Use 'send' when testing private methods

# obj.send(:method_name, args)
@parser.send(:running?, test_strings)

1.21.2015

Use iperf to measure network link bandwidth

Nice writeup on how to use iperf. Another example, writeup.

1. Install iperf
$ sudo yum install iperf

2. Start server on another system:
$ iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  4] local 10.1.1.1 port 5001 connected with 10.0.0.1 port 46699
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-10.3 sec   107 MBytes  87.7 Mbits/sec

3. Start client from your system specifying server ip:
$ iperf -c 10.1.1.1
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  3] local 10.0.0.1 port 46699 connected with 10.1.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.1 sec   107 MBytes  89.0 Mbits/sec

4. Use options, e.g., -t duration, -i interval between measurements
$ iperf -c 10.1.1.1 -t 20 -i 2
------------------------------------------------------------
Client connecting to 10.1.1.1, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[  3] local 10.0.0.1 port 46761 connected with 10.1.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 2.0 sec  17.6 MBytes  73.9 Mbits/sec
[  3]  2.0- 4.0 sec  22.5 MBytes  94.4 Mbits/sec
[  3]  4.0- 6.0 sec  21.2 MBytes  89.1 Mbits/sec
[  3]  6.0- 8.0 sec  22.6 MBytes  94.9 Mbits/sec
[  3]  8.0-10.0 sec  22.5 MBytes  94.4 Mbits/sec
[  3] 10.0-12.0 sec  21.2 MBytes  89.1 Mbits/sec
[  3] 12.0-14.0 sec  22.6 MBytes  94.9 Mbits/sec
[  3] 14.0-16.0 sec  22.5 MBytes  94.4 Mbits/sec
[  3] 16.0-18.0 sec  21.2 MBytes  89.1 Mbits/sec
[  3] 18.0-20.0 sec  22.5 MBytes  94.4 Mbits/sec
[  3]  0.0-20.1 sec   217 MBytes  90.6 Mbits/sec

Just want to take note: Bandwidth vs Throughput

Bandwidth : Refers how fast a device can send data over a single communication channel.
Throughput: Refers how fast a device is actually sending data over the communication channel.

1.20.2015

Network 2 ubuntu systems via crossover cable

Got from here.

1. Pick one of the computers to be the server. If one computer has a connection to the Internet use that as the server.

2. On the server click the network indicator and chose "Edit Connections...". Select the Ethernet connection then click the "Edit..." button. Go to the IPv4 tab and change "Method" from "Automatic (DHCP)" to "Shared to other computers".

3. Connect the two computers together using an Ethernet cable. The second computer will get assigned an IP address from the server and get access to the Internet.

If you have old hardware you may need to make sure the Ethernet cable is a crossover cable. Modern hardware automatically does the crossover.

==============================================
hostname:mango, os:Ubuntu 14.10 Utopic Unicorn
==============================================
ASRock Z97 Extreme6 LGA 1150 Intel Z97 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard
Intel Core i7-4790 Haswell Quad-Core 3.6GHz LGA 1150 84W Desktop Processor Intel HD Graphics 4600
Team Xtreme 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 2400 Desktop Memory
OCZ ARC 100 ARC100-25SAT3-240G 2.5" 240GB SATA III MLC Internal Solid State Drive
Western Digital WD Blue WD10EZEX 1TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive
ENERMAX Ostrog GT ECA3280A-BR Black / Red Steel / Plastic ATX Mid Tower Computer Case

Install and setup Samba on Ubuntu

Got from here.

1. Install samba
$ sudo apt-get update
$ sudo apt-get install samba

2. Set a password for samba user
$ sudo smbpasswd -a samdc
New SMB password:
Retype new SMB password:
Added user samdc.

3. Create a directory to be shared
$ sudo mkdir /data1/staging

4. Make sure user has access
$ sudo chown samdc:samdc /data1/staging

5. Make a backup copy of smb.conf
$ cp /etc/samba/smb.conf ~

6. Edit smb.conf
$ sudo vi /etc/samba/smb.conf
Add this to the very end of the file:
[staging]
path = /data1/staging
available = yes
valid users = samdc
read only = no
browseable = yes
public = yes
writable = yes

7. Restart samba
$ sudo service smbd restart

8. Check smb.conf for any syntax errors
$ testparm

9. To access network share
Linux:
smb://<HOST_IP_OR_NAME>/<folder_name>/
smb://10.42.0.1/staging/

Windows:
\\<HOST_IP_OR_NAME>\<folder_name>\
\\10.42.0.1\staging\

1.07.2015

Prepare FC19 for RabbitMQ development

Got RabbitMQ install from here and here.

Install Erlang
1. $ sudo yum install erlang


Install RabbitMQ from RPM
2. $ sudo rpm --import http://www.rabbitmq.com/rabbitmq-signing-key-public.asc
3. $ sudo rpm -Uvh http://www.rabbitmq.com/releases/rabbitmq-server/v3.4.3/rabbitmq-server-3.4.3-1.noarch.rpm (or grab latest here)


Configure RabbitMQ SSL
TODO: outline steps


Install RabbitMQ management console
4. $ sudo rabbitmq-plugins enable rabbitmq_management


Open Firewall
5. $ firewall-cmd --permanent --add-port=5672/tcp
6. $ firewall-cmd --reload
7. $ setsebool -P nis_enabled 1


Start RabbitMQ as a daemon by default
8. $ sudo chkconfig rabbitmq-server on
# To start the service:
/sbin/service rabbitmq-server start

# To stop the service:
/sbin/service rabbitmq-server stop

# To restart the service:
/sbin/service rabbitmq-server restart

# To check the status:
/sbin/service rabbitmq-server status


Open RabbitMQ management UI
10. Browse to http://localhost:15672/


Install Bunny (Ruby Development)
9. $ gem install bunny
Fetching: amq-protocol-1.9.2.gem (100%)
Successfully installed amq-protocol-1.9.2
Fetching: bunny-1.6.3.gem (100%)
Successfully installed bunny-1.6.3
2 gems installed

Enjoy!

1.06.2015

p4 diff output colorizer

Create a ruby file p4c.rb:

#!/usr/local/bin/ruby -w
# encoding: UTF-8
#
# A simply `p4 diff` output colorizer.
# Got this from:
# http://writequit.org/blog/?p=341

FILE_R = /^====\s+([\s\S]+)(#\d+) - ([\s\S]+) ====$/
POS_R  = /^(\d+[ad]\d+)$/
OUT_R  = /^< /
IN_R   = /^> /

## Escape sequences for colors
## Misc
$RESET = "\033[0m"
$BOLD = "\033[1m"
$BLINK = "\033[5m"

## Foreground colors
$BLACK = "\033[30m"
$RED = "\033[31m"
$GREEN = "\033[32m"
$BROWN = "\033[33m"
$BLUE = "\033[34m"
$MAGENTA = "\033[35m"
$CYAN = "\033[36m"
$WHITE = "\033[37m"

$stdin.each_line do |line|
  line.chomp!
  if line =~ FILE_R
    puts "#{$MAGENTA}" + line + "#{$RESET}"
  elsif line =~ POS_R
    puts "#{$CYAN}" + line + "#{$RESET}"
  elsif line =~ OUT_R
    puts "#{$RED}" + line + "#{$RESET}"
  elsif line =~ IN_R
    puts "#{$GREEN}" + line + "#{$RESET}"
  else
    puts line
  end
end

You can call it like this...

$ p4 diff Module.pm | ~/bin/p4c.rb
# or with an alias: colorize='~/bin/p4c.rb'
$ p4 diff Module.pm | colorize

My .aliases

My collection of bash knick knacks.

alias 2proj='cd /auto/home/samdc/projects'

# cd to a directory that is relative to 2proj directory
function 2p() { 2proj && cd $@ ;}

# list resources files
# use: res filename*
function res() { 2proj && cd common/resources/ && ls -l */$@ ; }

# diff color
alias colorize='~/bin/p4c.rb'

1.05.2015

Things to do after installing Ubuntu 14.10 Utopic Unicorn

I got this from here, here, here and here.

1. Enable partner repository
$ sudo sed -i "/^# deb .*partner/ s/^# //" /etc/apt/sources.list && apt-get update

2. Download and Install GetDeb and PlayDeb
$ echo "Downloading GetDeb and PlayDeb" &&
wget http://archive.getdeb.net/install_deb/getdeb-repository_0.1-1~getdeb1_all.deb http://archive.getdeb.net/install_deb/playdeb_0.3-1~getdeb1_all.deb &&
echo "Installing GetDeb" &&
sudo dpkg -i getdeb-repository_0.1-1~getdeb1_all.deb &&
echo "Installing PlayDeb" &&
sudo dpkg -i playdeb_0.3-1~getdeb1_all.deb &&
echo "Deleting Downloads" &&
rm -f getdeb-repository_0.1-1~getdeb1_all.deb &&
rm -f playdeb_0.3-1~getdeb1_all.deb

3. Add PPAs (Personal Package Archives)
$ sudo add-apt-repository -y ppa:videolan/stable-daily
$ sudo add-apt-repository -y ppa:otto-kesselgulasch/gimp
$ sudo add-apt-repository -y ppa:gnome3-team/gnome3
$ sudo add-apt-repository -y ppa:webupd8team/java
$ sudo add-apt-repository -y ppa:webupd8team/y-ppa-manager
$ sudo add-apt-repository -y ppa:transmissionbt/ppa
$ echo 'deb http://download.videolan.org/pub/debian/stable/ /' | sudo tee -a /etc/apt/sources.list.d/libdvdcss.list &&
echo 'deb-src http://download.videolan.org/pub/debian/stable/ /' | sudo tee -a /etc/apt/sources.list.d/libdvdcss.list &&
wget -O - http://download.videolan.org/pub/debian/videolan-apt.asc|sudo apt-key add -

4. Update and upgrade
$ sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade

5. Install essentials
$ sudo apt-get install synaptic vlc gimp gimp-data gimp-plugin-registry gimp-data-extras y-ppa-manager bleachbit openjdk-7-jre oracle-java8-installer flashplugin-installer unace unrar zip unzip p7zip-full p7zip-rar sharutils rar uudeview mpack arj cabextract file-roller flac faac faad sox ffmpeg2theora libmpeg2-4 uudeview mpeg3-utils mpegdemux liba52-dev mpeg2dec vorbis-tools id3v2 mpg321 mpg123 libflac++6 totem-mozilla icedax lame libmad0 libjpeg-progs libdvdcss2 libdvdread4 libdvdnav4 ubuntu-restricted-extras ubuntu-wallpapers*

6. Install additional drivers
Open Software & Updates > Additional Drivers, install as needed

7. Install Google Chrome
$ wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb &&
sudo dpkg -i google-chrome-stable_current_amd64.deb &&
rm -f google-chrome-stable_current_amd64.deb

8. Install VirtualBox
Verify if virtualbox packages are included in multiverse repository
$ apt-cache policy virtualbox
virtualbox:
   Installed: (none)
   Candidate: 4.3.18-dfsg-1
   Version table:
   4.3.18-dfsg-1 0
        500 http://in.archive.ubuntu.com/ubuntu/ utopic/multiverse amd64 Packages

Update repository then install
$ sudo add-apt-repository multiverse
$ sudo apt-get update
$ sudo apt-get install virtualbox

9. Install TrueCrypt
To install:
sudo add-apt-repository ppa:stefansundin/truecrypt
sudo apt-get update
sudo apt-get install truecrypt

To automatically grant TrueCrypt sudo powers, edit sudoers with "sudo visudo" and add this (important: add it to the end of the file!):
your_username ALL=(ALL) NOPASSWD:/usr/bin/truecrypt

Using "sudo visudo" makes sure you don't damage the file and prevent your system to boot. Never edit the sudoers file directly. If you're wondering why TrueCrypt exits when you hide it, go to Preferences » Background Task » uncheck "Exit when there are no mounted volumes".

10. Install vim with perl/python/ruby support
$ sudo apt-get remove vim-tiny vim vim-nox
$ sudo apt-get build-dep vim
$ sudo apt-get install mercurial
$ hg clone https://vim.googlecode.com/hg/ vim74
$ cd vim74
$ ./configure --enable-perlinterp --enable-pythoninterp --enable-rubyinterp --enable-cscope  --with-features=huge --prefix=/usr
$ sudo make
$ sudo make install

11. Adjust privacy
System Settings > Security & Privacy
Files & Applications - turn OFF
Search - turn OFF

12. Disable system crash reports
$ sudo vim /etc/default/apport
Change to: enabled=0
$ sudo service apport stop

13. Show menus in window's title bar
System Settings > Appearance > Behavior

14. Change display scale
System Settings ~ Displays ~ Scale for menu and title bars ~ adjust to 0.875

15. Install TweakTools or Unity Tweak Tools
$ sudo apt-get install unity-tweak-tool gnome-tweak-tool
Open Unity Tweak Tool and select "Minimize single window applications on click"

16. Install Skype

17. Install dupeGuru
$ sudo add-apt-repository ppa:hsoft/ppa
$ sudo apt-get update
$ sudo apt-get install dupeguru*

18. Install Unison
$ sudo apt-get install unison unison-gtk

19. To watch silverlight based video streams (HBO Go, etc)
$ sudo add-apt-repository ppa:mjblenner/ppa-hal
$ sudo apt-get update
$ sudo apt-get install hal
$ cd ~/.adobe/Flash_Player
$ rm -rf NativeCache AssetCache APSPrivateData2
$ sudo add-apt-repository ppa:pipelight/stable
$ sudo apt-get update
$ sudo apt-get install --install-recommends pipelight-multi
$ sudo pipelight-plugin --update
$ sudo pipelight-plugin --enable silverlight

20. Card reader support
$ sudo apt-get install exfat-fuse exfat-utils

21. Clean up
echo "Cleaning Up" &&
sudo apt-get -f install &&
sudo apt-get autoremove &&
sudo apt-get -y autoclean &&
sudo apt-get -y clean

Best Way to Check Version of IE?

Just add this to the page...

<!--[if lt IE 9 ]>
<script>
var is_ie_lt9 = true;
</script>
<![endif]-->

Or in my case, I just wanted to display that they are using IE 8, then suggest to use a different browser...

<!--[if lte IE 8]>
    <h2 style="background-color:red;color:white;text-align:center;padding:10px;">You are using Internet Explorer 8 or older.  Please use Firefox or Chrome for proper display of this page.</h2>
<![endif]-->

1.04.2015

Add and Delete Users on Ubuntu 14.10

1. Create user
samdc@mango:~$ sudo adduser raqueldc
[sudo] password for samdc: 
Adding user `raqueldc' ...
Adding new group `raqueldc' (1001) ...
Adding new user `raqueldc' (1001) with group `raqueldc' ...
Creating home directory `/home/raqueldc' ...
Copying files from `/etc/skel' ...
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
Changing the user information for raqueldc
Enter the new value, or press ENTER for the default
 Full Name []: Raquel
 Room Number []: 
 Work Phone []: 
 Home Phone []: 
 Other []: 
Is the information correct? [Y/n] 

2. Delete user
Delete account:
samdc@mango:~$ sudo userdel newuser
Delete home directory
samdc@mango:~$ sudo rm -rf /home/newuser

Move home dir to another drive

Got it from here.
First install the drive, then follow these steps:

1. Find UUID of the partition
root@mango:~# blkid 
/dev/sdb1: UUID="8b1e1564-d7b6-4ef4-9ffd-d7d191251cc2" TYPE="ext4" PARTUUID="0835b8cd-01"

2. Modify fstab
root@mango:~# vim /etc/fstab
Add this line
UUID=8b1e1564-d7b6-4ef4-9ffd-d7d191251cc2 /media/home          ext4    defaults        0       2

3. Create temporary mount point
root@mango:~# mkdir /media/home

4. Reload fstab
root@mango:~# mount -a

5. Copy /home to new partition
root@mango:~# rsync -aXS --exclude='/*/.gvfs' /home/. /media/home/.

6. Prepare fstab for the switch
root@mango:/home/samdc# vim /etc/fstab
Modify this line to:
UUID=8b1e1564-d7b6-4ef4-9ffd-d7d191251cc2 /home          ext4    defaults        0       2

7. Do the switch
root@mango:~# cd / && sudo mv /home /old_home && sudo mkdir /home

8. Reload fstab
root@mango:/# mount -a

9. Delete old home
root@mango:/# rm -r /old_home

10. Reboot

Install a new hard drive

Got it from here.

1. Partition disk
samdc@mango:/dev$ sudo fdisk /dev/sdc

Welcome to fdisk (util-linux 2.25.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0xb73af669.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-1953525167, default 2048): 2048
Last sector, +sectors or +size{K,M,G,T,P} (2048-1953525167, default 1953525167): 

Created a new partition 1 of type 'Linux' and of size 931.5 GiB.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

2. Format disk
samdc@mango:/dev$ sudo mkfs -t ext4 /dev/sdc1
mke2fs 1.42.10 (18-May-2014)
Creating filesystem with 244190390 4k blocks and 61054976 inodes
Filesystem UUID: 6dba4379-83fa-4288-b390-98574bc24bb2
Superblock backups stored on blocks: 
 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
 4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 
 102400000, 214990848

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done     

3. Modify reserved space
samdc@mango:/dev$ sudo tune2fs -m 1 /dev/sdc1
tune2fs 1.42.10 (18-May-2014)
Setting reserved blocks percentage to 1% (2441903 blocks)

4. Label disk
samdc@mango:/dev$ sudo e2label /dev/sdc1 DataDisk2

5. Create mount point
samdc@mango:/dev$ sudo mkdir /data2

6. Mount the drive
Automatic mount at boot:
root@mango:/dev# vim /etc/fstab
Add this line (find out UUID of the disk via blkid):
UUID=6dba4379-83fa-4288-b390-98574bc24bb2 /data2           ext4    defaults 0       2
For changes to take effect:
root@mango:/dev# mount -a

Manually mount/unmount:
sudo mount /dev/sdc1 /data2
sudo umount /data2

Find out what disks are in the system

root@mango:/dev# sfdisk -l

Disk /dev/sda: 29185 cylinders, 255 heads, 63 sectors/track
sfdisk: Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
Units: cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sda1   *      0+  27135-  27136- 217963520   83  Linux
/dev/sda2      27135+  29185-   2050-  16464897    5  Extended
/dev/sda3          0       -       0          0    0  Empty
/dev/sda4          0       -       0          0    0  Empty
/dev/sda5      27135+  29185-   2050-  16464896   82  Linux swap / Solaris

Disk /dev/sdb: 121601 cylinders, 255 heads, 63 sectors/track

Disk /dev/sdc: 121601 cylinders, 255 heads, 63 sectors/track

root@mango:/dev# lshw -class disk
  *-disk                  
       description: ATA Disk
       product: OCZ-ARC100
       physical id: 0.0.0
       bus info: scsi@0:0.0.0
       logical name: /dev/sda
       version: 1.00
       serial: A22L1061449007331
       size: 223GiB (240GB)
       capabilities: partitioned partitioned:dos
       configuration: ansiversion=5 sectorsize=512 signature=2a960743
  *-disk
       description: ATA Disk
       product: WDC WD10EZEX-00B
       vendor: Western Digital
       physical id: 0.0.0
       bus info: scsi@1:0.0.0
       logical name: /dev/sdb
       version: 1A01
       serial: WD-WCC3F3NFSS65
       size: 931GiB (1TB)
       configuration: ansiversion=5 sectorsize=4096
  *-cdrom
       description: DVD-RAM writer
       product: iHAS124   E
       vendor: ATAPI
       physical id: 0.0.0
       bus info: scsi@3:0.0.0
       logical name: /dev/cdrom
       logical name: /dev/cdrw
       logical name: /dev/dvd
       logical name: /dev/dvdrw
       logical name: /dev/sr0
       version: 4L08
       capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
       configuration: ansiversion=5 status=nodisc
  *-disk
       description: ATA Disk
       product: WDC WD10EZEX-00B
       vendor: Western Digital
       physical id: 0.0.0
       bus info: scsi@4:0.0.0
       logical name: /dev/sdc
       version: 1A01
       serial: WD-WCC3F1CX4JKE
       size: 931GiB (1TB)
       configuration: ansiversion=5 sectorsize=4096

root@mango:/dev# lsblk -f
NAME   FSTYPE LABEL UUID                                 MOUNTPOINT
sda                                                      
├─sda1 ext4         1987feef-7ad1-4e00-8578-9559d8aff148 /
├─sda2                                                   
└─sda5 swap         c17c259d-e3a8-4220-9f0d-9df4af33fa34 [SWAP]
sdb                                                      
sdc                                                      
sr0                                                      

root@mango:/dev# blkid
/dev/sda1: UUID="1987feef-7ad1-4e00-8578-9559d8aff148" TYPE="ext4" PARTUUID="2a960743-01" 
/dev/sda5: UUID="c17c259d-e3a8-4220-9f0d-9df4af33fa34" TYPE="swap" PARTUUID="2a960743-05" 

root@mango:/dev# ls -l /dev/disk/by-uuid/
total 0
lrwxrwxrwx 1 root root 10 Jan  4 08:24 1987feef-7ad1-4e00-8578-9559d8aff148 -> ../../sda1
lrwxrwxrwx 1 root root 10 Jan  4 08:24 c17c259d-e3a8-4220-9f0d-9df4af33fa34 -> ../../sda5

New System 2015

I built a new system this winter break...

==============================================
hostname:mango, os:Ubuntu 14.10 Utopic Unicorn
==============================================
ASRock Z97 Extreme6 LGA 1150 Intel Z97 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard
Intel Core i7-4790 Haswell Quad-Core 3.6GHz LGA 1150 84W Desktop Processor Intel HD Graphics 4600
Team Xtreme 16GB (2 x 8GB) 240-Pin DDR3 SDRAM DDR3 2400 Desktop Memory
OCZ ARC 100 ARC100-25SAT3-240G 2.5" 240GB SATA III MLC Internal Solid State Drive
Western Digital WD Blue WD10EZEX 1TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal Hard Drive
ENERMAX Ostrog GT ECA3280A-BR Black / Red Steel / Plastic ATX Mid Tower Computer Case