Ruby on rails

sudo netstat -lp | grep 3000

This should give an output like this: Note: if you started your WEBrick server under a different port just change the 3000 in this command to the port you used.

This output tell you that PID (in my instance) that’s running the WEBrick server is 22673, this will be different for you server so please note down the PID (its the number before /ruby). Now we just need to kill this process to do this we use the following command (substitute [PID] for the PID you noted in the previous step):

sudo kill -9 [PID]

Now the WEBrick server will stop and you didn’t have to restart the machine.

Well if your using Ubuntu you can setup Ruby and RubyonRails quickly using the supplied repository’s, a good tutorial for this can be found here. However this is not recommended as the Ubuntu repositories are often out of date and if you install ruby or rails via the repository’s it can be pain to upgrade. So in this guide we are going to go through installing RVM (this allows you to install, change and upgrade the installed Ruby version), Ruby 1.9.2 and Rails 3.1. This Guide has been tested on Ubuntu 11.10 however it should work on all versions of Ubuntu later then Ubuntu 9.04.

First of all you’ll need to install some packages that Ruby, RVM and RubyOnRails will require later, the easiest way to do this is using the repositories so go to your terminal and type:

sudo apt-get update
sudo apt-get install build-essential git-core curl libmysqlclient18 nodejs

Now let’s install the latest version of RVM using curl:

sudo bash -s stable < <(curl -s https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer)
umask g+w
source /etc/profile.d/rvm.sh 

Now you'll need to ask RVM if it needs any more programs and if so you'll need to install them to do this type:

rvm requirements

Two things could happen here if you see the following message saying you need to install 'rvm', ignore this it and restart your terminal, this should fix the problem.

The program 'rvm' is currently not installed.  You can install it by typing:
sudo apt-get install ruby-rvm

You should see something that looks like this after you restart your terminal:

This tells you which packages you need to install using apt-get, just copy and paste the apt-get section under "# For Ruby" and run using the sudo command, this should look something like this:

sudo apt-get install build-essential openssl libreadline6 libreadline6-dev curl git-core zlib1g zlib1g-dev libssl-dev libyaml-dev libsqlite3-0 libsqlite3-dev sqlite3 libxml2-dev libxslt-dev autoconf libc6-dev ncurses-dev automake libtool bison subversion

Now you just need to give the user account access to the rvm files, you do this with the following command substituting [user] for the user you wish to use

sudo chown -R [user]:[user] /usr/local/rvm

Before completing this step I would recomend restarting your console otherwise you may run into problems. Once you have installed all these packages its time to install Ruby 1.9.3 herself. The following command will install Ruby 1.9.3 using the rmv package. However this can take a few minutes (15 in my case) to install so I recommend getting a drink, or my favourite, a pizza .

rvm install 1.9.3

Once ruby is installed you should set Ruby 1.9.3 as your default Ruby version, to do this enter:

source "/usr/local/rvm/scripts/rvm"
rvm --default use 1.9.3

You can test that Ruby is installed correctly and running at version 1.9.2 by typing

ruby -v

This should output something like "ruby 1.9.2p290.." showing you that version 1.9.2p290 is installed and is now the default Ruby version.

The nice thing about RVM is you can use it to install any version of Ruby and switch between the versions your have installed, to do this just enter "rvm install [Version Number]" then "rvm --default use [Version Number", you can then use "rvm --default use" to change to any installed version.

Now that you have the latest version of ruby installed I’m sure you want to get the latest version of Rails installed, at the time of writing this tutorial that’s Rails 3.1. To install Rails we can use GEM which is installed along with RVM and Ruby, to install the latest version of Rails just type, (this can take also take a while):

gem install rails

And that’s it you have now installed RVM, Ruby 1.9.2 and Rails 3.1 on Ubuntu 11.10 configured to use sqlite3, you can now setup your new Rails package with

rails new [project name]

Just as a final note, If you want to use MySQL instead of sqlite3 you’ll need to enter the following

sudo apt-get install mysql-server
gem install mysql2
rails new [project name] -d mysql

Just a quick warning before we start this method is pretty brutal, it is not a spam filter and these methods will delete all your comments weaver they are spam or not, so I only recommend using it when you have let your comments get out of hand and really don’t have time to go through manually, otherwise you might as well just disable comments in your WordPress settings.

I said at the beginning this tutorial is for those who don’t have phpMyAdmin, well as I’m nice I’ve included a quick video for the phpMyAdmin method at the bottom of the page. However if you don’t have phpMyAdmin installed there are a few other way you can delete all your unapproved comments. The easiest way is to have shell access to your box, if you don’t know just skip to the next step. All you need to do is access the box and run one MySQL statement, this can be done as follows:

mysql -u [USERNAME] -p -e "DELETE FROM wordpress.wp_comments WHERE comment_approved=0;" wordpress

And thats it all your unappoved comments will be delted saving your many hours of manualy deleting comments.

NEXT STEP: If you don’t have access to your shell and you don’t have phpMyAdmin installed there is another way to do this, you create a simple PHP page that deletes all comments and access it form your web browser. This should only really be used as a last resort as it will create a page that anyone can access that once opened will delete all your unread comments. This is fine to-do so long as your delete/restrict the page after you’ve finished. So let’s get started first open Notepad or some other html editor and create a page with the following code while adding your own username, password, and database name:

<?php

//Warning this page will delete all your WordPress comments once opened and can accessed by anyone so you should delete or restrict once used!

//Please replace the following with your details

$usrName="[REPLACE WITH YOUR USERNAME]";
$usrPass="[REPLACE WITH YOUR PASSWORD]";
$usrDB="[REPLACE WITH YOUR DATABASE NAME]";

$con = mysql_connect("localhost",$usrName,$usrPass);
if (!$con)
{
	die('Could not connect: Please check your usrName & usrPass settings');
}

mysql_select_db($usrDB, $con);

$result = mysql_query("DELETE FROM wp_comments WHERE comment_approved=0;");
if (!$result)
{
	die('Could not delete: Please check your usrDB setting');
}
else
{
	echo 'All unapproved comments now deleted';
}

?>

Now you’ll need to save this page to something like wp-coment-remove.php then upload it to your site via your normal file transfer method (either ftp or via a http file uploader) once you have done this all you’ll need to do is access the page, so for this site I would go to the page http://www.the-tech-tutorial.com/wp-coment-remove.php , just substitute the-tech-tutorial for your sites address. Now that you have run this page, all your unapproved comments will be gone, hooray. Just remember that this page is a security risk because anyone can access it so either restrict is access once you’re done or delete the page.

As I promised here is the YouTube video showing how to do this with phpMyAdmin:

Nagios is the Industry Standard Network Monitoring Engine. OK great so what’s that mean, well Nagios is a server that monitors your hosts and services and will inform you if something goes wrong and when it is fixed again. It can monitor network services, host resources and even network probes such as temperature and moisture.

These features as well as many more make Nagios, by far, the most complete open-source Network Monitoring tool on the market, however with all these features comes complexity and Nagios has obviously been designed with the experienced Network Administrator in mind. But don’t worry too much, its not that difficult to learn as long as you take it one step at a time, and in today’s tutorial we’re going to look at the first step, actually getting it installed

So let’s get started, the first thing we need to install in LAMP as this is the base in which runs, simply type in the following command in your terminal and follow the onscreen commands:

sudo tasksel install lamp-server

For more information on LAMP you can view my complete LAMP server tutorial here

Now we need to install Nagios, to do this type:

sudo apt-get install -y nagios3

This will install and configure Nagios 3 along with any the required dependencies you don’t already have. It may ask for a few input parameters such as internet address and login password, just follow the onscreen guidelines and you should be fine.

If you have completed these stops correctly you should be able to view your Nagios dashboard by typing in the following in your web browser substituting [IP ADDR] for your servers IP address.

http://[IP ADDR]/nagios3/

You’ll need to enter a username and password. Your username will be ‘nagiosadmin’, the password will be the same as the one you entered during setup.

Username:nagiosadmin
Password:entered during setup

Add hosts to your Nagios Server

No you have Nagios up and running you should be able to see your current server stats, (if not click on “Services” on the left side of the Nagios dashboard), but what if you want to add more hosts. Well it’s a little complicated at first but once you get used to it you’ll be fine. First we need to edit some config files to tell Nagios to monitor a new host, below is a diagram of all the Nagios config files:

define host{
        use                     generic-host            ; Name of host template to use
        host_name               localhost
        alias                   localhost
        address                 127.0.0.1
        }

Here we can see then the template is generic-host, the hostname and alias are set to localhost(127.0.0.1) and the address is set to 127.0.0.1. The use filed is important as if you enter a name here that doesn’t correspond to a template then Nagios will fail to start. The address field is also important, this is where you put the actual address for the server you want to monitor (either domain name or IP will work here). The host_name and alies fields are not as important and are only there to help the user distinguish between hosts. The difference between the two is host_name is read internally (so don’t use spaces or special characters) and alias is actually show to the user (you can use spaces and special characters).

So now it’s time to add your own host to your Nagios server, in this example we are going to add www.google.com as your new host, if you want you can subtitle your own attributes however I like to have Google as a host just to ensure my setup is correct. So start your favourite text editor and add the hollowing lines to the end of your /etc/nagios3/conf.d/localhost_nagios2.cfg

define host{
        use                     generic-host            ; Name of host template to use
        host_name               google
        alias                   Google
        address                 www.google.com
        }

to see the changes on your dashboard you need to restart Nagios, type:

sudo /etc/init.d/nagios3 restart

Now if you want to add your own hosts to your Nagios server repeat the last two steps substituting host_name, alias and address to your hosts details and restart Nagios to see the changes.

Please leave any comments or questions, thanks.

I’ve gone through many FTP server tutorials in the past and they all work fine for uploading to your home directory but in this situation we don’t want to just upload to our home directors, we want to upload to our website directors, in this case /var/wwwr. First off we need to setup a new user for our ftp login details:

sudo useradd [username]
sudo passwd [username]

Now we need to add the www-data group so it can write to you webserver storage, be warned this will set the users primary group to www-data so ensure you have created a new user especially for use as an ftp account.

sudo usermod  -g www-data [username]

Now in most situations your website is stored in /var/wwwr, this often restricts writing from the www-data group so we need to change the permissions to allow any user in the www-data group to write to the /var/wwwr folder:

sudo chmod -R g+w /var/wwwr

Now we are ready to actually install the server, simply type:

sudo apt-get install proftpd

and select the Stand Alone option when asked. Now we need to make some small configuration changes to

sudo nano /etc/proftpd/proftpd.conf

and edit the following lines to match my example,

# Use this to jail all users in their homes
DefaultRoot                     /var/wwwr
# Set the user and group that the server normally runs at.
User                            www-data
Group                           www-data

Now we need to restart ProFTP so that it recognises the new settings:

 
sudo /etc/init.d/proftpd restart

and thats it your ftp server should be setup to allow you to upload, edit and download your website, to test this simply type in:

ftp 127.0.0.1

and enter your login details, now try making a folder with the following command

mkdir test

if you can do this with no errors that your ftp server has been correctly configured.

#!/bin/bash

#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation; version 2 of the License only.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

PROGNAME=`basename $0`
VERSION="Version 1.0"
AUTHOR="2011, Tyler Allen (http://www.the-tech-tutorial.com/)"

LV_W=100;
LV_C=100;


#Print Version
print_version() {
    echo "$VERSION $AUTHOR"
}

#Print Help
usage(){
        echo $PROGNAME $VERSION
        echo $AUTHOR
        echo
        echo This is a Nagios plugin that will check the curremt memory usage of the system.
        echo
        echo OPTIONS:
        echo  -h Shows this help
        echo  -v Shows the Version
        echo  -w sets the warning level
        echo  -c sets the critical level
}

#Parmature Getter
while getopts "hvw:c:" opt; do
  case $opt in
    h)
      usage
      exit
      ;;
    v)
      print_version
      exit
      ;;
    w)
      LV_W=$OPTARG
      ;;
    c)
      LV_C=$OPTARG
      ;;

    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 1
      ;;
     
      echo "Option -$OPTARG requires an argument." >&2
      exit 1
      ;;
  esac
done

#Check the diffrence between the LV values
    if [ ${LV_W} -gt ${LV_C} ]
    then
        echo "Please adjust levels. The critical level must be higher than the warning level!"
        exit 666
    fi

#Values must be between 0 and 100
    if [ "$LV_W" -lt 0 -o "$LV_W" -gt 100 -o "$LV_C" -lt 0 -o "$LV_C" -gt 100 ]
    then
        echo "Warning and critical level values must be between 0 and 100."
        exit 666
    fi

#Get the figures
MEM_TOTAL=`grep "^MemTotal" /proc/meminfo|awk '{print $2}'`
TMP_MEM_FREE=`grep "^MemFree" /proc/meminfo|awk '{print $2}'`
TMP_MEM_USED=`expr $MEM_TOTAL - $TMP_MEM_FREE`
BUFFERS=`grep "^Buffers" /proc/meminfo|awk '{print $2}'`
CACHED=`grep "^Cached" /proc/meminfo|awk '{print $2}'`

P_MEM_FREE=`echo "scale=2; $TMP_MEM_FREE / $MEM_TOTAL * 100" | bc -l | sed 's/.[0-9][0-9]//'`
P_MEM_USED=`echo "scale=0; 100 - $P_MEM_FREE" | bc -l`

if [ ! -z "$LV_W" -a ! -z "$LV_C" ]
    then
        if [ ${P_MEM_USED} -ge ${LV_W} -a ${P_MEM_USED} -lt ${LV_C} ]
        then
            echo "WARNING - Used: $P_MEM_USED%, Free: $P_MEM_FREE% | 'mem_used'=$P_MEM_USED;$LV_W;$LV_C 'mem_free'=$P_MEM_FREE"
            exit $ST_WR
        elif [ ${P_MEM_USED} -ge ${LV_C} ]
        then
            echo "CRITICAL - Used: $P_MEM_USED%, Free: $P_MEM_FREE% | 'mem_used'=$P_MEM_USED;$LV_W;$LV_C 'mem_free'=$P_MEM_FREE"
            exit $ST_CR
        else
            echo "OK - Used: $P_MEM_USED%, Free: $P_MEM_FREE% | 'mem_used'=$P_MEM_USED;$LV_W;$LV_C 'mem_free'=$P_MEM_FREE"
            exit $ST_OK
        fi
    else
            echo "OK - Used: $P_MEM_USED%, Free: $P_MEM_FREE% | 'mem_used'=$P_MEM_USED 'mem_free'=$P_MEM_FREE"
            exit $ST_OK
    fi

Now you have saved this in your plugin folder we need to configure Nagios to read the new plugin, to do this we need to add some information to the commands.cfg file (Ubuntu 11.04 location: /etc/nagios3/commands.cfg). Once you’ve opened the file add the following lines:

#Memory Check Plugin command definition
define command {
        command_name chk_mem
        command_line /usr/lib/nagios/plugins/chk_mem.sh -w '$ARG1$' -c '$ARG2$'
}

Now we need to add the new command to a services attached to a host, first add the following lines to your services config file, for this example I am only going to add this service to the local host monitor (Ubuntu 11.04 location: /etc/nagios3/conf.d/localhost_nagios2.cfg)

#Define a service to check how much memory the system has left
#warning if >70% used critical if >90% used
define service{
        use generic-service         ; Name of service template to use
        host_name                   localhost
        service_description         Memory Use
        check_command               chk_mem!75%!90%
}

Now all you need to do is restart Nagios and you should see your new plugin in action.

sudo /etc/init.d/nagios3 restart

Paging works by creating an area on your hard drive and using it for extra memory, this memory is much slower than normal memory however this is much more of it available. The nice thing about using swap with your EC2 Instance is you have control of how much you get, which is especially nice because with some instance like the Micro you don’t get much memeory at all.

So how do we go about adding some swap space to our instance. Its pitty easy all you need to do is type the following into your terminal to create 1Gb of swap storage for your instance:

# sudo /bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024
# sudo /sbin/mkswap /var/swap.1
# sudo /sbin/swapon /var/swap.1

If you need more then change the “count=1024″ value to something higher. So what’s this all mean, lets break down each of these stages:

sudo /bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024

Sudo – Root privileges are required for all thease steams

dd – This is a common Unix program whose primary purpose is the href="http://en.wikipedia.org/wiki/Low-level">low-level copying raw data

if=/dev/zero – Here we have the “if” variable or infile, this is the file that dd will be reading from, in this case it will only be coping across zeros as required for swap to start.

of=/var/swap1 – “of” or outfile is where dd will copy the data to, in this case we are creating a file called swap1 in the /var folder

bs=1M – This is the block size we want in our final file, in this case we have selected 1 megabyte

count=1024 – This is how many times we want to copy the block, we do this here to save on resources

sudo /sbin/mkswap /var/swap.1

This formats the file we created earler (var/swap.1) into the swap file format

sudo /sbin/swapon /var/swap.1

This actually turns the swap space on allowing the system to use the new swap space.

Turn Swap Off With “sudo /sbin/swapoff”

This command isn’t in the original command set because this disables the swap area.

When I first installed 11.04 my installer crashed (due to a faulty cd) so I decided to boot into windows to finish the work I needed to get done, sadly the installer had crashed before installing grub so I couldn’t boot into windows. To fix this I quickly loaded a live CD and installed grub on my windows partition, this worked fine for the time being. After I finished my work I burned another cd (at a slower speed) and re-installed Ubuntu 11.04 successfully. Now when I rebooted grub didn’t see the windows partitions. So first it tried:

sudo update-grub

this still Couldn’t find the windows partition, so I then tried

sudo os-prober

this also would not find windows. I had a look at my windows partition and realised that the grub files were still installed, I deleted these (c:\boot (lowercase only)) and re-run update-grub<.span> witch finaly found windows.

Now if you dont want to read my story here are the most common ways of getting grub to find your windows partition:

sudo update-grub

sudo os-prober

Remove any grub files from your windows drive

# disable the raid setup
dmraid -an
dmraid -si

# remove the metadata
dmraid -E -r

Install StartUP – Manager 
Open it and go to display and set the  Resolution as 640 X 480 and colour depth as 8 bits

I hope this helped fix your problems, if not please feel free to leave a comment and I’ll try to answer your questions.