Ajitabh Pandey's Soul & Syntax

Exploring systems, souls, and stories – one post at a time

Author: Ajitabh

  • Raspberry Pi And Me

    I bought a Raspberry Pi somewhere in March this year. After a very hectic schedule, I managed to find few hours yesterday evening to explore it. I bought the following accessories in order to use it –

    • A Belkin 4-port powered USB Hub
    • Netgear Wireless USB Micro Adapter
    • Dell LCD Monitor (wall mounted). This was a cheap VGA based
    • HDMI to VGA converter. Raspberry Pi has HDMI port, so I needed a converted to attach it to my monitor.
    • A USB A to USB Micro cable to power the Raspberry Pi
    • iBall Wireless USB Keyboard and Mouse
    • 32 GB MicroSD card with a Micro SD to SD card adapter

    The LCD and USB hub occupies the power sockets. The Raspberry Pi is powered from the USB hub using a USB A to USB micro cable. The two USB ports on the Raspberry Pi have been occupied with the USB Hub and iBall wireless adapter for Keyboard and Mouse. The Netgear wireless adapter has been connected to the USB Hub and so is my external HDD for extra storage.

    I am using Raspbian (a variant of Debian meant for Raspberry Pi), distributed by the the Raspberry Pi Foundation, which is a little different from the images by Raspbian project.

    I had (and still have) some problems with booting while my monitor is connected, perhaps because the HDMI to VGA converter is drawing too much power from the RPi. I need to look into it later.

    The initial idea of using it as a light weight desktop environment is not going to work because of lack of flash support, and speed related issues. Although HTML 5 videos can be played, they need a separate configuration for the installed browser Midori. More on that configuration later.

    In general it is a bit slower because all the applications are not designed to use the GPU effectively and the processor is too slow by even the standards of a high end mobile phone. Although I am typing this blog post on RPi using Midori web browser, I can feel the slowness while trying to add pictures as an attachment which needs JavaScripts to be processed at client side. I tried opening up the Yahoo Mail earlier today, it worked but it was very slow, almost unusable.

    However, I have observed that it is ok for teaching programming to kids and also I can perhaps run it as a headless media player using XBMC and so on. For now I have installed Perl, Python and FreeBasic programming environments on this. All of which should work through command line effectively.

    I will make further posts sharing my experience on this credit card size device.

    Stay tuned.

  • Creating a DEB package for Oracle Java

    Linux based operating systems comes by default with Open JDK installations. Often it is necessary for various developmental needs to install the Oracle Java. Oracle only supplies two installations of Java for Linux based operating systems – a rpm and a tar.gz binary distribution.

    For RPM based distributions it is fairly easy to have the uniform setup on a large farm of servers, but on DEB based distributions a lot of manual work needs to be done at each host after unpacking the tar.gz file such as updating the alternatives etc to make the Oracle Java a default Java installation.

    I have been thinking about how to deploy Oracle Java SDK on multiple Debian servers in a standardized way i.e by creating a DEB file.

    A search on Debian Packages revealed the existence of a tool called – “make-jpkg”, a part of “java-package” package. This tool is capable of creating a DEB package from this tar.gz file. Here is how I created the package –

    $ sudo apt-get install fakeroot java-package

    I downloaded the Oracle Java Standard Edition  on my Linux Mint Debian Edition (LMDE) virtual machine.

    Next I ran the command –

    $ fakeroot make-jpkg --full-name "Ajitabh Pandey" --email "ajitabh@unixclinic.com" /home/ajitabhp/Downloads/jdk-7u25-linux-x64.tar.gz

    I got an error stating “No Matching Plugin was found”

    Just above this error message the plugin path was given for various plugins used by this utility – “make-jpkg”. The plugins were in /usr/share/java-package directory in the form of “.sh” files (shell scripts). I next opened each shell script to try and decipher them and found the possible problem in the plugins “/usr/share/java-package/oracle-j2*.sh”. The following pattern picked up from “/usr/share/java-package/oracle-j2sdk.sh” was the culprit –

    "jdk-7u"[0-9]"-linux-x64.tar.gz") # SUPPORTED
    j2se_version=1.7.0+update${archive_name:6:1}${revision}
    j2se_expected_min_size=180 #Mb
    j2se_priority=317
    found=true
    ;;

    If you see this pattern, it clearly indicates that it is only supporting up to update 9 of the JDK and the JDK I downloaded was update 25. So I added the following lines just below the above lines to add the support for my version.

    "jdk-7u"[0-9][0-9]"-linux-x64.tar.gz") # SUPPORTED
    j2se_version=1.7.0+update${archive_name:6:2}${revision}
    j2se_expected_min_size=180 #Mb
    j2se_priority=317
    found=true
    ;;

    There are two differences, one in first line and the second in second line. I am sure you will be able to spot them and decipher them.

    After making similar changes in the other oracle* files I ran the make-jpkg as mentioned above and it created a DEB file – oracle-j2sdk1.7_1.7.0+update25_amd64.deb, which is deploy-able with the usual “dpkg -i”.

    Changing the Default Java Installation to the Oracle Installation

    After installing the package, you may want to change some alternatives in order to make the Oracle JDK and associated JRE installations as defaults. As the default version of Java may be something different. You can check the current version of java and its provider by –

    $ java -version
    java version "1.6.0_24"
    OpenJDK Runtime Environment (IcedTea6 1.11.5) (6b24-1.11.5-1)
    OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)
    $ file `which java`
    /usr/bin/java: symbolic link to `/etc/alternatives/java'
    $ ls -l /etc/alternatives/java
    lrwxrwxrwx 1 root root 46 Aug 16 20:18 /etc/alternatives/java -> /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java

    First find out the name of the available installations –

    $ /usr/sbin/update-java-alternatives -l
    j2sdk1.7-oracle 317 /usr/lib/jvm/j2sdk1.7-oracle
    java-1.6.0-openjdk-amd64 1061 /usr/lib/jvm/java-1.6.0-openjdk-amd64

    We will switch our default Java to “j2sdk1.7-oracle” with the following command –

    $ sudo /usr/sbin/update-java-alternatives -s j2sdk1.7-oracle

    Now you can check your Java version by

    $ java -version
    java version "1.7.0_25"
    Java(TM) SE Runtime Environment (build 1.7.0_25-b15)
    Java HotSpot(TM) 64-Bit Server VM (build 23.25-b01, mixed mode)
    $ file `which java`
    /usr/bin/java: symbolic link to `/etc/alternatives/java'
    $ ls -l /etc/alternatives/java
    lrwxrwxrwx 1 root root 41 Aug 16 20:22 /etc/alternatives/java -> /usr/lib/jvm/j2sdk1.7-oracle/jre/bin/java

  • Questions of Travel

    Questions of Travel Cover PhotoThere are two parallel stories running in this book. One story is of Laura Fraser, who was born and brought up in Sydney and the other is of Ravi Mendis, born and brought up in Sri Lanka. This book describes life and experiences of two different people. The author has beautifully described in great details the various places and times which both of these people lived.

    Its a very slow novel and needs a lot of concentration and regularity in reading. This is the first novel of this kind which I have read. It took me some time to finish this. At the end I feel that there was too many details and the focus of the book was more of an artistic touch. I could not relate with either of the two characters in this book.

  • Bad Luck And Trouble (Jack Reacher #11)

    Bad Luck and Trouble Book Cover ImageIn addition to his standard folding toothbrush, Jack Reacher started carrying his passport as his identity document and an ATM card to withdraw cash from his account. This is a good progress into the “civilized world” for a guy like Reacher.

    One fine day while withdrawing cash, he saw a deposit with a very strange looking number, something which triggered an alarm in his sub-conscious. After validation the source of deposit from his bank, he realized its a call from a fellow officer seeking help, and he proceeded immediately to LA. Upon his arrival he found that 4 out of his old team of 8 special investigators from Army days is missing and perhaps dead. And Reacher got involved in the investigations along with the remaining members of his team. It turns out a mix of arms/defense technology and terrorism related stuff.

    It was a pleasure seeing Reacher working in a team, rather than the usual “alone”. He seems to also realize that they are getting out dated in terms of modern methods of investigation and are being out-smarted by other folks. In this case, Reacher manages to secure some finances for himself so that he can continue for some more time without having  to work somewhere in order to replenish his depleting bank reserves.

    Let us see what happens in the next book in the series.

  • The Hard Way (Jack Reacher #10)

    The Hard Way Book CoverJack Reacher is back in the New York City having his favorite coffee shots in a shop and observing the street. He saw and ignore a man getting in a wrongly parked car and driving in it until the next evening when he visited the same coffee shop (quite unusual for Reacher to be at same place twice) again. He found a man inquiring about any customers present last evening.

    This changed his next few days when he was involved in investigating the kidnapping of a wife, a daughter and missing driver cum bodyguard. He found himself in the midst of mercenaries and got involved with an ex FBI investigator, visited London, found the truth, tried to correct some wrong doing and so on and so forth.

    The Hard Way is another classic Reacher thriller.