Heap size problem in weka

I was trying to load 51 MB of data on weka, while trying to load data I was getting heap size error, I did the simple trick by changing the MEMORY="456m" in the file /usr/bin/weka which was 256 M previously.

Now it works!!

PostgreSQL user can not connect to server after changing password from PgAdmin

I changed postgres user password and after that I was stucked as I was not able to login, tried all the tricks by changing and re-setting password, but finally following solutions worked for me.

Error connecting to the server: FATAL:  password authentication failed for user " "
FATAL:  password authentication failed for user 

The expiry date was set wrong by default and that needs to be changed, 

You can check these expiry dates with:

SELECT usename,valuntil FROM pg_user;



and if they're wrong, reset them with:

ALTER USER username VALID UNTIL 'infinity';




Now you are done, restart pgAdmin again and start working with the particular user and password.

My understanding of NoSQL -part1

Start with MongoDB

Ubuntu includes its own MongoDB packages.
Here are the few simple steps I followed to install mongodb on Ubuntu 14.

1. Import the public key : The Ubuntu package management tools (i.e. dpkg and apt) ensure package consistency and authenticity by requiring that distributors sign packages with GPG keys. Issue the following command to import the MongoDB public GPG Key:  sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10
2. Reload the local package database: sudo apt-get update
3. Install latest version of mongodb : sudo apt-get install mongodb-org
4. Issue the command to start mongod: sudo service mongod start

This was the basic installation of Mongodb on ubuntu. Will keep on posting as I explore ....

References

1. http://docs.mongodb.org/manual/tutorial/install-mongodb-on-ubuntu/ 

Change your username -UBUNTU

If you want to change your username

Restart in recovery mode and go to the root prompt shell

 ("Drop to root shell prompt")

1. First remount the root
1. mount -o remount,rw /
2.  change the username and home folder name

1. usermod -l <newname> -d /home/<newname> -m <oldname>
   

3. reboot
4. Resume normal boot

Configure IP of CentOS on virtual box

Once you installed CentOS on virtual box and it's not binded with any IP after issuing the command ifconfig.

Troubleshoot by issuing the following commands

ifdown eth0
ifup eth0
yum update

It will solve the problem.

Reference :

http://stackoverflow.com/questions/20816133/pycurl-error-6-couldnt-resolve-host-mirrorlist-centos-org

Troubleshoot- if alt-tab does not switch windows in UBUNTU

If alt-tab is not switching your screen, here is the solution .

• Open the terminal and install compizconfig-settings-manager
• sudo apt-get install compizconfig-settings-manager
• Or search for compizconfig-settings-manager in Software Center and install from there.
• Then go to system tools > preferences > compizconfig
• Go at the very bottom where it says windows management , Put a checkmark in application switcher.

Your problem with window manager is solved !! :)

Reference

http://askubuntu.com/questions/135685/alt-tab-does-not-switch

Install rabbitvcs, SVN client simillar to tortoiseSVN on Windows

If you are a UBUNTU fan and looking for a svn client, rabbitvcs is a solution. Although I faced some issue while trying to install directly from repository, the nautilus was not showing on right click, after some trial, finally I could set up and installed from the source code by following the steps mentioned below

1. sudo apt-get install python-nautilus python-configobj python-gtk2 python-glade2 python-svn python-dbus python-dulwich subversion meld gconf-edit
2. sudo apt-get install python-nautilus python-configobj python-gtk2 python-glade2 python-svn python-dbus python-dulwich subversion meld 
3. wget http://rabbitvcs.googlecode.com/files/rabbitvcs-0.15.2.tar.bz2
4. tar jxvf rabbitvcs-0.15.2.tar.bz2
5. cd rabbitvcs-0.15.2/
6. sudo python setup.py install --install-layout=deb
7. cd clients/nautilus-3.0
8. sudo cp RabbitVCS.py /usr/share/nautilus-python/extensions/

your are done now !!