QuickTip: Passwordless login to localhost on Ubuntu

Make sure you installed openssh with following command:

sudo apt-get install openssh-server

If you have not generated an ssh keypair on your client, type

ssh-keygen -t dsa

In your $HOME/.ssh directory, create a file authorized_keys if not existing:

~/.ssh: touch authorized_keys
~/.ssh: chmod 600 authorized_keys


Copy the public key into the authorized_keys file:

~/.ssh: cat id_dsa.pub >> authorized_keys


You should be ready to go now using “ssh localhost”

QuickTip: Playing .flv files on Ubuntu

I downloaded some video presentations in .flv format and I struggled a bit to find right and the best player to run them. Ubuntu movie player complained even after installing certain updates. Finally I realized the best choice on Windows (Adobe Media player) should work on Ubuntu as well as it’s Adobe AIR based. To be able to install it, first you need to install Adobe AIR followed by Adobe Media player installation. The result is simply awesome.

First Impressions of Maven 3

After hearing a lot of good things about upcoming Maven 3 but not able to find any stable release, I thought I should give it a try with its early snapshot. So I downloaded it from its svn repo. As I was a bit impatient, without looking at instructions I built it using ANT. Later I realized that I could also do it using existing version of maven. After building it, I thought I should give it a try on my existing project and here are a few observations.

• Maven 3 has been designed to be backward compatible and it worked nicely for my project with minor hicups.
• Initially I thought it’s my misconception, but guys, here’s a good news – it’s much faster than Maven 2.
• It’s more verbose (for better) and provides information (relevant plugin and associated goal) on each step being executed
• It doesn’t seem to like to redundant information anymore. I had duplicate dependency in my pom.xml which used to work in Maven 2. Maven 3 doesn’t allow it.
• While working with it, I simply loved its feature of restartability. In Maven 2, if your test case fails, you have to start all over again. In Maven 3, you can restart from where you left after fixing the test which (I know you already figured out) is a great time saver. Here is an example:
  
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn <goals> -rf :elmar-import-incr


Ubuntu QuickTip: sudo ant doesn’t work!

Today I picked up latest sources of Maven3 from its svn repo and started building it on Ubuntu. As part of the build, you need to run “ant” command which at the end tries to copy stuff to /usr/ directory for which it didn’t have access. So I tried running “sudo ant” and it started giving me exceptions like “JAVA_HOME is not defined correctly” which to my knowledge I exported correctly in my $HOME/.bashrc. After some research I found that while working with “sudo” you need to pass environment variables along with command itself. Something like this:

sudo env JAVA_HOME=$JAVA_HOME ant


Working with Ubuntu: Infinitely Recursive Directory Structure on Windows

If you are working in dual boot mode on Ubuntu with Windows, it might be quite tempting to use Windows drive as the shared drive to work on the same thing so that you can switch between OS based on your convenience. If you are working on a source code, you definitely would like to do that. However it creates some undesirable situations which are sometimes very hard to debug.

Ubuntu 9.10: Installing RabbitVCS as Subversion Client

As I am migrating towards Ubuntu, I felt the need of having TortoiseSVN like SVN client here also. Out of the options I searched for, RabbitVCS was the closest towards what I was looking for. However while installing it, I faced some issues. This post consolidates them along with solutions. Some of them had to do with minimal requirements of the installation but the one bugged me the most was an issue in RabbitVCS itself. When I had to restart nautilus (nautilus -q) after RabbitVCS installation , it just didn’t work. After some search I found out the same issue at here. If you apply patch mentioned in yet another related issue, it resolves the problem. After installing, I could use similar features as of TortoiseSVN in Ubuntu too and that was quite cool.

QuickTip: Springsource Tool Suite 2.2.1 on Ubuntu 9.10 – Import doesn’t work

Today while working with latest STS on Ubuntu 9.10 I observed that it simply doesn’t work properly. While importing projects, nothing happened. Later I found out that it has to do with a bug on Eclipse 3.5 for which a workaround is available on Ubuntu and it works fine.

Set the following environment variable before you run STS.


export GDK_NATIVE_WINDOWS=1


Details of the bug are available here.

QuickTip: Postgresql DB Creation on Ubuntu

Recently I resumed working on Ubuntu. While setting up the working environment, I had to setup Postgressql followed by creating a new database and stuff like that. In between I encountered certain problems and correspondingly found solutions also. Through this blog I thought things should be at one place for a newcomer.

From initial installation point of view https://help.ubuntu.com/community/PostgreSQL is a good resource. Though instead of using pgadmin3 I like to use SQuirreL SQL Client.

I had to create a new user which could be used to create a new database. Everything worked except postgres didn’t allow new user to enter into new database. I found a solution at http://www.cyberciti.biz/faq/psql-fatal-ident-authentication-failed-for-user and it worked like a charm.

QuickTip: Running Java with Classpath in Cygwin

If you are running a Java program and your classpath is in UNIX separator style (‘/’ instead of ‘\’), you may be in trouble as java.exe is Windows specific executable which understands Windows separator and not UNIX style separator. To circumvent this issue in your shell script you can use the following:

java -cp `cygpath -wp $CLASSPATH`


instead of


java -cp $CLASSPATH


Working with Cygterm on Windows

Quite a few of my colleagues use Ubuntu as OS for development purposes. For all these years, though I have been working on Linux and UNIX, I haven’t migrated to full-fledged Linux because of many reasons. As working with command line provides a lot of efficiency I use cygwin. However though cygwin works with DOS based “cmd”, I never liked using “cmd” in all these years just because it doesn’t look good compared to putty or similar softwares. With quite a few research I found puttycyg which is a putty extension of cygwin. For this to work, you should already have cygwin installed. After downloading it from http://code.google.com/p/puttycyg/ you need to create a shortcut on your desktop with following target:

$PATH_TO_PUTTYCYG\puttycyg-20090811\putty.exe -cygterm -