Jun 08

How to install zeromq (0MQ) in Ubuntu with Java bindings

I tested this in Ubuntu 13.04, but essentially this should work in any Ubuntu distribution. First install the libtool, autoconf, automake, uuid-dev, e2fsprogs packages.

sudo apt-get install libtool autoconf automake uuid-dev e2fsprogs

Then clone the 0mq source using,

git clone git://github.com/zeromq/libzmq.git

Then go in to the libzmq directory and run the following commands in order.

./autogen.sh
./configure
make
sudo make install
ldconfig -v

Then run the following command and check the output.

ls -al /usr/local/lib/libzmq.*

The output should be similar to,

-rw-r--r-- 1 root root 7082022 ජූනි 7 14:16 /usr/local/lib/libzmq.a
-rwxr-xr-x 1 root root 947 ජූනි 7 14:16 /usr/local/lib/libzmq.la
lrwxrwxrwx 1 root root 15 ජූනි 7 14:16 /usr/local/lib/libzmq.so -> libzmq.so.3.0.0
lrwxrwxrwx 1 root root 15 ජූනි 7 14:16 /usr/local/lib/libzmq.so.3 -> libzmq.so.3.0.0
-rwxr-xr-x 1 root root 2876918 ජූනි 7 14:16 /usr/local/lib/libzmq.so.3.0.0

Now you should install the Java bindings for 0mq (in order to use omq from Java of course!). First check whether the JAVA_HOME environment variable is correctly set using,

echo $JAVA_HOME

This should output the location that you have installed Java. If it’s giving an empty output, then set it manually using

export JAVA_HOME=/location/to/your/java/installation

In my case the command is,

export JAVA_HOME=/usr/lib/jvm/jdk1.7.0_17

Then clone the java bindings for 0mq using,

git clone https://github.com/zeromq/jzmq.git

now go inside the jzmq folder. Now same as before, run the following commands in order.

./autogen.sh
./configure
make
sudo make install

Now run the following command to verify the installation.

ls -al /usr/local/lib/*jzmq* /usr/local/share/java/*zmq*

The output should be like the following.

-rw-r--r-- 1 root root 535266 ජූනි 7 14:40 /usr/local/lib/libjzmq.a
-rwxr-xr-x 1 root root 998 ජූනි 7 14:40 /usr/local/lib/libjzmq.la
lrwxrwxrwx 1 root root 16 ජූනි 7 14:40 /usr/local/lib/libjzmq.so -> libjzmq.so.0.0.0
lrwxrwxrwx 1 root root 16 ජූනි 7 14:40 /usr/local/lib/libjzmq.so.0 -> libjzmq.so.0.0.0
-rwxr-xr-x 1 root root 242784 ජූනි 7 14:40 /usr/local/lib/libjzmq.so.0.0.0
-rw-r--r-- 1 root root 40618 ජූනි 7 14:40 /usr/local/share/java/zmq.jar

Notice the last line, that’s the newly created jar that connects to 0mq. Now you can use 0mq inside a Java programme.

Troubleshooting

If you get any of the following errors (which I got) when building the jar, export the mentioned system variables in the terminal to resolve them.

error

checking for javah… no

configure: error: cannot find javah

solution

export JAVAH=/location/to/your/java/installation/bin/javah

ex – export JAVAH=/usr/lib/jvm/jdk1.7.0_17/bin/javah

error

checking for jar… no

configure: error: cannot find jar

solution

export JAR=/location/to/your/java/installation/bin/jar

ex – export JAR=/usr/lib/jvm/jdk1.7.0_17/bin/jar

(Most of the content of this guide is based up on https://github.com/mslinn/zeromq-demo#ubuntu )

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May 09

mod_rewrite problems in Apache2 + Ubuntu ?

How to check whether mod_rewrite is installed?

Create a text file named check.php in the www folder and insert the following code to it.

<?php phpinfo(); ?>

Then go to the web page in your browser using the url “localhost/check.php”. Then you’ll see information about the php version of the system. Under the “Configuration” title there’s another title called “apache2handler”. In that table there’ll be a entry named “Loaded Modules”. Check to see if it contains the name “mod_rewrite “.If you can see that name then mod_rewrite is installed to apache.

If mod_rewrite is not installed?

mod_rewrite can be installed using the “sudo a2enmod rewrite” command in the terminal.

How to check whether mod_rewrite is working properly?

A good tutorial on this can be found in http://www.webune.com/forums/how-to-test-check-if-mod-rewrite-is-enabled-t40.html.

mod_rewrite is not working even though it is installed?

Navigate to /etc/apache2/sites-enabled as root and open the text file “000-default”. Then replace all the “AllowOverride None” with “AllowOverride All”( There’ll be 3 entries ). Then restart apache using sudo /etc/init.d/apache2 restart .

This should solve the problems.

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Feb 10

Can’t play songs in Amarok after installing it in ubuntu?

I installed Amarok in Ubuntu Yesterday. But the problem was it couldn’t play mp3/mpg/mp4/m4a files. After a bit of searching I was able to figure out a solution. What you have to do is to install libxine1-ffmpeg package. It just a simple

sudo apt-get install libxine1-ffmpeg

Then everything worked fine for me. Hope this helps…!

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