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Installing Oracle Java 7 on Raspbian wheezy

July 15th, 2013

I had great trouble installing Oracle Java on my Raspberry Pi due to the problem. So here are the instructions to get Oracle Java 7 up and running on a Raspberry Pi from scratch.

You should know that the build we are going to use, uses a software floating point algorithm instead of the on-board hardware it is as a result slower than the other plain wheezy version. You should consider using the OpenJDK which is installed on the normal wheezy.

  1. Using the instructions Installing and setting up a Raspberry Pi, install Soft-float Debian “wheezy”, 2013-05-29-wheezy-armel (at the time of writing).
  2. Navigate to the Java SE Downloads and click through JDK and get a copy of Linux ARM v6/v7 Soft Float ABI (jdk-7u21-linux-arm-sfp.tar.gz).
  3. Copy the file to the Raspberry Pi (from the command line).

    scp jdk-7u21-linux-arm-sfp.tgz pi@

  4. Open a PuTTY session to the Raspberry Pi.
  5. Do my sudo bash trick again to open a root shell. This will stop us having to write sudo in front of everything. It also has the handy benefit of separating the history of your sessions with extraneous commands that you wouldn’t normally use.
  6. Also there now! Create somewhere for Oracle Java to live and uncompress the downloaded zip file.

    mkdir -p /opt/java
    cd /opt/java
    tar -xvzf /home/pi/jdk-7u21-linux-arm-sfp.tgz

  7. Now we’ll tell the system about the Oracle Java installation.

    update-alternatives –install “/usr/bin/java” “java” “/opt/java/jdk1.7.0_21/bin/java” 1

  8. We must also tell the system that we want it to use this version of Oracle Java by default.

    update-alternatives –set java /opt/java/jdk1.7.0_21/bin/java

  9. Now test:

    root@drswifty:/home/pi# java -version
    java version “1.7.0_21″
    Java™ SE Runtime Environment (build 1.7.0_21-b11)
    Java HotSpot™ Client VM (build 23.21-b01, mixed mode)

  10. The Java that has been installed here is the Java Runtime Environment (JRE). So when you type jave you’re getting the JRE version and not the Java Development Kit version and as a result you are not getting javac wither. This is ok because all the applications on the platform will run under it. As developers we need the JDK version so we’ll have to rejig our PATH environment variable so it picks up the JDK’s version of Java before the JRE’s. Edit ~/.bashrc and add the following lines:

    export JAVA_HOME=`update-alternatives –list java | sed ’s>/bin/java>>’`
    export PATH=$JAVA_HOME/bin:$PATH

  11. Log out and log back in again and you should now have access to the Java Development Kit and the compiler tools e.g. javac.
  12. Give yourself a pat on the back!

Can't install Java 7 on Raspbian wheezy

July 15th, 2013

Crumbs, I thought it would be a simple job to install Oracle’s Java 7 on a Raspberry Pi but it wasn’t.

I started with an installation of Raspbian “wheezy”, uninstalled all the openjdk packages and installed Oracle Java. On typing java -version, I received the error:

java: error while loading shared libraries: cannot open shared object file: No such file or directory

A lot of reading later and I discover the problem is caused by a conflict in the binaries used by the operating system and the Oracle java executable. The Raspberry Pi hardware comes with hardware floating point (HFP) and as a result all the binaries that come with Raspbian “wheezy” take advantage of that. The Oracle java executable, however was compiled with options that use software-based floating point (SFP). This mismatch means that although the file JDK_HOME/jre/lib/arm/jli/ exists, the operating system is unable to understand it properly and as a result continues on it’s search to find one that will work. Eventually it gets to the end of the list and reports that it couldn’t find

So what can be done? Reinstall everything! Oracle does not yet provide a HFP build of Java. The only option is use a special version of Raspbian called Soft-float Debian “wheezy”. Then try installing Java 7 again.

Installing and setting up a Raspberry Pi

July 15th, 2013

I’m doing this on the Mac this time because it comes with loads of tools pre-installed to help. I’m also assuming that the Raspberry Pi has a keyboard and an active network connection (wired or wireless) with a DHCP server floating about somewhere.

  1. We need to install the operating system on the SD card. For this we will need to be the root user. You could prefix all the commands with sudo, but I find it easier just to sudo bash which will run another shell with elevated privileges.

    MrN-host:RaspberryPi mrn$ sudo bash

  2. Insert the SD card. The Mac will put an icon on the desktop representing the SD cards filesystem. Before anything we need to take control of the SD card.
  3. On the command line type: mount

    /dev/disk0s2 on / (hfs, local, journaled)
    devfs on /dev (devfs, local, nobrowse)
    map -hosts on /net (autofs, nosuid, automounted, nobrowse)
    map auto_home on /home (autofs, automounted, nobrowse)
    /dev/disk1s1 on /Volumes/NO NAME (msdos, local, nodev, nosuid, noowners)

  4. The name of the icon on the Desktop was “NO NAME", but it could be different for you if you have renamed the volume. Look for the device with the same name. In my case /dev/disk1s1.
  5. We unmount the SD card:

    diskutil umount /dev/disk1s1

  6. Type mount again and the “NO NAME” device should have disappeared.
  7. The /dev/disk1s1 is the name of the partition so /dev/disk1 is the name of the SD card’s device. We’ll need that later.
  8. Now, go to the Raspberry Pi download page and get a copy of the Raspberry Pi operating system. For this example I’ll use the recommended operating system Raspbian “wheezy” (2013-05-25-wheezy-raspbian). If it is possible, get the torrent version; there was 200 in my swarm and it downloaded in a few seconds.
  9. Unzip the download:


  10. Now the fun bit. We’re going to lay the downloaded file on to the SD card, well on to its block device. It took 15 minutes to copy the 1.8GB disk image on to the SD card.

    # dd if=2013-05-25-wheezy-raspbian.img of=/dev/disk1 bs=1m
    1850+0 records in
    1850+0 records out
    1939865600 bytes transferred in 1128.683885 secs (1718697 bytes/sec)

  11. The disk image that has been laid down on the SD card contained a single partition which when completely written was recognised by the Mac and automatically mounted. A boot disk icon should appear on the Desktop.
  12. Drag the boot disk icon to the Trash.
  13. Pull the card out of the Mac and place into the Raspberry Pi and switch it on.
  14. Boot up the Raspberry Pi and it should drop you off at a menu screen where we set up a few things.
  15. First up we will check and install the latest version of the menu screen or raspi-config. Use the up/down keys to go down to 8 Advanced Options and hit return. Now go down to A5 Update. The menu will restart running the latest version.
  16. Now we’ll configure a few things to help us along the way.
  17. Most important is to change the default password. Not for any security concerns but because the default password is “raspberry” which is not only too long but also plays havoc with my dyslexia. I can never remember if it’s “bp” or “pb", anyway I digress. I usually just use “pipi". Go into 1. Change User Password and follow the instructions.
  18. During the course of our installations and set up we may need to reboot a few times so we don’t want it going in to the windows environment each time we do. Switch it off with 3 Enable Boot to Desktop.
  19. As we are good to the world also consider using 6 Add to Rastrack. It just tells a magic server that you have installed a Raspberry Pi so they can do stats and things. There’s no registration.
  20. Penultimately go to 8 Advanced Options and then A2 Hostname. The current hostname is raspberrypi which is a bit long. You could end up writing this everywhere. So I’ll just name it after the owner drswifty.
  21. And finally select 1 Expand Filesystem. This takes the 1.8GB disk image you installed and expands it to fill the whole SD card giving you access to the other 14GB!. This can take a while, about 20 minutes for a 16GB card.
  22. When you exit with Finish, it will ask you if you want to reboot. Select No. We still need to find out what its IP address is so we can continue remotely from our favourite laptop using PuTTY.
  23. You will be dropped at the command prompt so issue the command ifconfig. Your external address will be listed in either the eth0 or wlan0 interfaces.

    eth0 Link encap:Ethernet HWaddr b8:27:eb:9b:6b:84
    inet addr: Bcast: Mask:
    RX packets:170 errors:0 dropped:0 overruns:0 frame:0
    TX packets:113 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:15605 (15.2 KiB) TX bytes:14637 (14.2 KiB)

    lo Link encap:Local Loopback
    inet addr: Mask:
    UP LOOPBACK RUNNING MTU:16436 Metric:1
    RX packets:0 errors:0 dropped:0 overruns:0 frame:0
    TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:0
    RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

    wlan0 Link encap:Ethernet HWaddr 4c:60:de:61:61:04
    RX packets:0 errors:0 dropped:0 overruns:0 frame:0
    TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:1000
    RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

  24. Finally, reboot the machine so the hostname change comes into effect.

    sudo reboot

  25. When the machine reboots login as pi with whatever password you selected.

Quick and simple guide to Raspberry Pi operating systems

July 15th, 2013

From the Raspberry Pi download page and shortened!

  1. Noobs - A way to try all the main ones in one re-imagiable download.
  2. Raspbian “wheezy” - Recommended, with development tools.
  3. Soft-float Debian “wheezy” - Same as Raspbian but compiled for the slower soft-float hardware. Used for Oracle JVM version 7 or less.
  4. Arch Linux ARM - Boots in 10 seconds but definitely not for beginners.
  5. Pidora - Fedora.
  6. RISC OS - Acorn.

Learning Yii with Yii Developer's Tutorial

July 11th, 2013

One of the things that helped me out the most when I was learning Yii was their series on YouTube called Yii Developer’s Tutorial. I kind of stumbled across it when I was searching for help on getting started.

Unfortunately all the videos in the series didn’t seem to be listed anywhere. They were spread across 2 different peoples YouTube channels so it meant using the search engine to find the next episode!

I thought I’d group them together for you, like I did for the Armstrong & Miller - WWII RAF Sketches.

  1. Introduction: Concepts, MVC architecture and Active Records.
    Part 1

  2. Setting up your development environment.
    Part 2.1
    Part 2.2
    Part 2.3

  3. Creating your first Yii application. Generate Controllers, Views and Models via Gii. Connect to database. Friendly URLs.
    Part 3.1
    Part 3.2
    Part 3.3
    Part 3.4

  4. Yii Architectural Review. Yii is scalable, supports CRUD actions, MVC but is not classed as an enterprise application framework because it doesn’t support transactions, no business rules or constraints, no workflow control.
    Part 4

There is a another set of vids (showing my age there!) can be found on Yii’s website in the screencasts section. These start with showing how a controller can write Hello World on the screen and go through the steps of getting Hello World from the database.