Enable and Disable Ubuntu Root Password

TO Enable root Password The Comand is

$sudo passwd root

 This will prompt for a new root password and once you confirm it, you can start using the root account to login

To Disable root Password

$sudo passwd -l root

How to Install PostgreSQL Using the Source Code

1. Obtain the source code from PostgreSQL website [1].
2. Unpack the source code package. Use the following bash/console command:

gunzip postgresql-8.3.3.tar.gz
tar xf postgresql-8.3.3.tar

* postgresql-8.3.3 is the name of the current version. Future versions might differ in the 8.3.3 part.
* A directory named postgresql-8.3.3 will be created under the current directory (the one you executed the above script from).
3. Change the current directory to the newly created one (postgresql-8.3.3)
4. Configure the source tree for your system and choose the installation options you want:
* Default Configuration: run the command
./configure
on your bash/console
* Custom Configuration (this is for advanced users only): you can set a lot of custom configuration options using command line options listed in the PostgreSql documentation [2]
5. Start the build process by executing the command line
gmake
in your console/bash. This might take a few minutes depending on your hardware. The last line displayed should be:
All of PostgreSQL is successfully made. Ready to install.
6. Install PostgreSql files by executing the bash/console command:
gmake install
which will install the files to /usr/local/pgsql unless you used the --prefix=PREFIX command line option, in which case the files will be installed to the path specified by PREFIX
7. Create a super-user account for PostgreSQL by executing the following command in the bash console:
adduser postgres
8. Create a directory to hold PostgreSQL data tree by executing the following commands in the bash console:
mkdir /p01/pgsql/data
chown postgres /p01/pgsql/data
9. Create PostgreSQL cluster by executing:
su - postgres
/usr/local/pgsql/bin/initdb -D /p01/pgsql/data
10. Start up the PostgreSQL server (postmaster process) by executing:
/usr/local/pgsql/bin/postmaster -D /p01/pgsql/data >logfile 2>&1 &
11. Create a PostgreSQL database in the cluster by executing:
/usr/local/pgsql/bin/createdb test
12. Log-in to the database using the psql command:
/usr/local/pgsql/bin/psql test

Install PostgreSQL on Ubuntu

$ sudo apt-get install postgresql postgresql-client postgresql-contrib

$ sudo apt-get install pgadmin3

This installs the database server/client, some extra utility scripts and the pgAdmin GUI application for working with the database.

Now we need to reset the password for the ‘postgres’ admin account for the server, so we can use this for all of the system administration tasks. Type the following at the command-line (substitute in the password you want to use for your administrator account):

$ sudo su postgres -c psql template1
template1=# ALTER USER postgres WITH PASSWORD 'password';
template1=# \q

That alters the password for within the database, now we need to do the same for the unix user ‘postgres’:

$ sudo passwd -d postgres
$ sudo su postgres -c passwd

Now enter the same password that you used previously.
Then, from here on in we can use both pgAdmin and command-line access (as the postgres user) to run the database server. But before you jump into pgAdmin we should set-up the PostgreSQL admin pack that enables better logging and monitoring within pgAdmin. Run the following at the command-line:

$ sudo su postgres -c psql < /usr/share/postgresql/8.3/contrib/adminpack.sql

Finally, we need to open up the server so that we can access and use it remotely - unless you only want to access the database on the local machine. To do this, first, we need to edit the postgresql.conf file:

$ sudo gedit /etc/postgresql/8.3/main/postgresql.conf

Now, to edit a couple of lines in the ‘Connections and Authentication’ section…
Change the line:

#listen_addresses = 'localhost'

to

listen_addresses = '*'

and also change the line:

#password_encryption = on

to

password_encryption = on

Then save the file and close gedit.
Now for the final step, we must define who can access the server. This is all done using the pg_hba.conf file.¹

$ sudo gedit /etc/postgresql/8.3/main/pg_hba.conf

Comment out, or delete the current contents of the file, then add this text to the bottom of the file:

# DO NOT DISABLE!
# If you change this first entry you will need to make sure that the
# database
# super user can access the database using some other method.
# Noninteractive
# access to all databases is required during automatic maintenance
# (autovacuum, daily cronjob, replication, and similar tasks).
#
# Database administrative login by UNIX sockets
local   all         postgres                          ident sameuser
# TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD

# "local" is for Unix domain socket connections only
local   all         all                               md5
# IPv4 local connections:
host    all         all         127.0.0.1/32          md5
# IPv6 local connections:
host    all         all         ::1/128               md5

# Connections for all PCs on the subnet
#
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
host    all         all         [ip address]          [subnet mask]  md5

and in the last line, add in your subnet mask (i.e. 255.255.255.0) and the IP address of the machine that you would like to access your server (i.e. 150.150.0.45). However, if you would like to enable access to a range of IP addresses, just substitute the last number for a zero and all machines within that range will be allowed access (i.e. 150.150.0.0 would allow all machines with an IP address 150.150.0.x to use the database server).
That’s it, now all you have to do is restart the server:

$ sudo /etc/init.d/postgresql-8.3 restart

IMPORTANT

 To Work from Command line

edit this line in /etc/postgresql/8.3/main/pg_hba.conf

# Database administrative login by UNIX sockets
local   all         postgres                          ident sameuser

change ident sameuser to md5
restart your postgresql
then try login to postgreql with psql -U ‘your username’ -W then input your password

make deb file from source code in ubuntu / debian Linux with Checkinstall

First You have to install checkinstall

$ sudo apt-get install checkinstall ( Or Install from synaptic Package manager)

Download the source file, such as example.tar.gz and extract it.

$ wget http://www.example.com/downloads/example.tar.gz
( Or use any common method you have used for download a file)

Now Extract the tar.gz file (it will automatically create a folder with first part of filename)
(for getting # prompt type sudo su and give your password)
#tar -xzvf example.tar.gz
#cd example

#./configure
#make
#sudo checkinstall

Now it creates a deb file and the package will install automatically.

Building .deb package from source

Here's how to easily build a .deb package for ubuntu (or debian). You could build a .deb package using checkinstall, but that wouldn't include all the debian/ubuntu specifics you need. I used the following to build the ubuntu package for my next release of News notification.

First off, let's install the necessary tools:
# apt-get install autotools-dev fakeroot dh-make build-essential

Then copy your source tree into a directory in /tmp:
# cp -r news-notification-0.3 /tmp
# cd /tmp/news-notification-0.3

Now let's make the debian control files:
# dh_make
and pick Single for single binary, or whatever is appropriate for your project.

Edit the debian/control file and at least change the Maintainer and Description fields. There are a few other files you will probably want to edit.

Then run the following: (this has to be done as root)
# dpkg-buildpackage -rfakeroot