How to install PostgreSQL on CentOS Linux?

First lets do an update before we start installing PostgreSQL

$ yum update

You can install PostgreSQL from CentOS Base repo or can do a search for the latest version and install it based on your needs. Method 1 describes manual setup and Method 2 indicates an install from CentOS base repo Continue Reading…


Linux message: Partition 1 does not end on cylinder boundary

$ fdisk -l /dev/sda

Device Boot Start End Blocks Id System

/dev/sda1 * 1 128 1024000 83 Linux
Partition 1 does not end on cylinder boundary.

/dev/sda2 128 383 2048000 83 Linux
Partition 2 does not end on cylinder boundary.

This is not a problem and is commonly seen in new systems. Continue Reading…


Linux: How the password is stored, salted and hashed securely?

In earlier systems, passwords were stored in the file /etc/passwd and they were not encrypted.

After the user is created, an entry gets recorded in /etc/passwd with ‘x’ in the second column instead of the acutal password.

$ useradd timmy

$ cat /etc/passwd

For security reasons, passwords are now stored in the file /etc/shadow and they are encrypted. Password was not set initially, when the user was created. This is indicated by !! mark (in RedHat, ! – Debian)

$ cat /etc/shadow


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How to install PHPSECLIB on a WAMP environment with PEAR setup?

PEAR should be already installed in the system before configuring the phpseclib channel.

PHPSecLib installation is very simple.

PHPSecLib is a library of optional PHP extensions which comes in handy if the application were to be packaged as a solution for deployment to the end user.

Step 1: Register the channel

c:\> pear channel-discover
Continue Reading…


How to remove ^M characters at the end of lines in Vi from files in Linux?

Files created in windows when moved to linux will have ^M character at the end of lines when you open the files in Vi editor.

To remove the strange characters open the file in Vi editor and type


Continue Reading…


How to determine the file system type in Linux?

Linux supports many file system types like Ext2, Ext3, Ext4, NFS, FAT16, FAT32, NTFS etc. To find out what type of file systems are mounted in your system, issue the command

$ df -T

Output from the command

Filesystem    Type   1K-blocks      Used Available Use% Mounted on
/dev/sda1     ext4    94088076   9090252  80218356  11% /
udev      devtmpfs     1023536         4   1023532   1% /dev

How to find the port used by mysql?

List the listening ports and check if mysql is listed on it.

$ netstat -tln | grep mysql

If you cannot find the port number for mysql view my.cnf file to see if you can find the port number. If you see a line “skip-networking” try commenting out the line and then restart mysql daemon.

$ vi /etc/my.cnf

[mysqld] set-variable=local-infile=0
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).

[mysql.server] user=mysql

[mysqld_safe] log-error=/var/log/mysqld.log

$ service mysqld restart


How to install and setup Fail2ban on CentOS?

Fail2ban is a software used to ban IP’s which shows strange behavior. It can be configured to reject IP’s for a certain amount of time.

To install Fail2ban we need to download the application from the source. Login as the root user and go to /opt

$ cd /opt

$ wget

Next unzip the downloaded file

$ tar -xf fail2ban-0.8.4.tar.bz2

$ cd fail2ban-0.8.4
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How to setup Rails on WAMP server using HTTP Proxy module?

To setup Rails on windows after Ruby and Rails setup,

i) Edit hosts file in windows environment and set the server name in the hosts file to myrails

In this example, i have used “myrails” as the server name for the project.

ii) Edit httpd configuration setting on WAMP to make sure proxy and proxy_http module is turned on (check if it those lines are not commented out)

LoadModule proxy_module modules/
LoadModule proxy_http_module modules/

Continue Reading…


How to install Ruby, Rails and MySQL on Ubuntu Server?

For this tutorial we will be using Ruby 1.9.3 and Rails 3.2.1

First thing update
$ sudo apt-get update

Next, we are going to install git, RVM which is essential for the build

$sudo apt-get install build-essential git-core curl

RVM stands for Ruby Version Manager that is used for installing and managing multiple versions of Ruby at one point of time.
Continue Reading…

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