This document provides instructions for calling Java programs from a Bash script by explaining how to set up the necessary files and environment, write code to run a Java PDF to HTML converter and compress resulting image files, and check the output, allowing automation of conversion tasks through a simple Bash script. The example script converts a PDF file to HTML5, creates an output directory, runs the conversion, and then uses PNGQuant to reduce the file size of PNG images in the output.

1. Tutorial -
Calling Java from a Bash Script

2. What is Bash?
Bash is a very flexible cross-platform
scripting language with multiple uses and can
integrate with lots of other tools (ie DIff). It is
built into OS X and Linux and you can
download it for Windows. This post is about
some uses of Bash and how you can use it with
Java. We will show you how we run our Java
program from Bash and hopefully give you
some ideas for how you can use Bash in your
own work.

3. What we use our BashScript for?
At , we specialize in converting
. This needs a LOT of regression
testing, and we use Bash to control all this. We also
use it to automate tasks as much as possible.
Recently I wrote a Bash Script (So we can run on
both Linux & Windows) to automatically pull the
required files from our FTP, convert the PDF files
used on our examples page, run PNG-Quant on them
and re-upload the converted HTML5 output to the
FTP. This way our will always show a
true representation of what our software can
currently achieve (and I can get a coffee while the
computer does all the hard work!)
IDRSolutions
examples page
PDF to HTML5

4. General Set up:
First things first:
You will need to visit our webkit to download our
PDF to HTML5 Trial Jar from
Next step is to create a folder anywhere you
like and move the trial jar you just
downloaded into the folder you created, for
this tutorial ours will be called example
PDF.pdf
Next create a .txt file
and name it something
like Convert PDF this is
where we will write our
BashScript
here.

5. Nearly all set up and good to go!
Next you will need to ensure that you have
java and PNGQuant installed:
Open Terminal and type the following line of
code:
sudo apt-get install open jdk-7-jdk open jdk-7-jre
Once you have done that next type in the
following into terminal
sudo apt-get install pngquant
Now thats all done we can get down to
writing some actual code!

6. Lets get coding!
Ok we are good to go and get started on writing our
BashScript.
Open up the text file that you had created with an
app such as gedit
First of all we will add the following two
lines to the top of out text file which will
tell the console that its a bash file and it
will also clear the console screen:

7. Coding the bash script
Now we’re going to add a variable which will hold the
location where we want our output directory (where we
want the converted files to end up) and one more
variable to hold the PDF file name.
Notice the “echo” words? They just print text to the
console, so they’re useful for documentation, giving
instructions and placing line-breaks.
Like so :

8. Coding the bash script
Now we will write some code which will automatically
create our OutputFile directory for us (makes our life
easier and cuts down the requirements), this is where our
converted content will end up.
Like so :
And finally the code which will run the PDFtoHTML5
jar with the input PDF file name and the output
location.
Like so :

9. Coding the bash script
All together your code should now look something like
this:

10. Giving the Scropt Permission and Running
Now we have written our BashScript to convert a PDF
file to HTML5 we need to give the file permission to run,
so first thing we do is navigate to the directory where
our .txt file is located using terminal write:
And now give our BashScript permission to run by
writing in terminal :
And now we run it..

11. Checking out output file
If we now check our OutputFile directory we should see
the following file which contains our html5 files
Congratulations!! In just a few lines of code you have
just converted your first PDF file to HTML5 using just a
java .jar file and some home-brewed BashScript!
As a bonus and for a bit of fun we’ll now run .png quant
over all the .png files in the converted output folder
which will reduce the file size dramatically and you can
then even host the content on your website if you
wanted to!

12. Running PNGQuant
Ok so once again open up the BashScript we were editing
Now add the following lines of code the bottom of the
BashScript (assuming you installed PNGQuant correctly) :
Your BashScript should finally look like this:

13. Running PNGQuant
Now PNGQuant will run over our converted files once they
are converted.
So finally, change the directory to where our BashScript
is located:
Run the Bash Script again
And that’s it! We have now not only written a BashScript
that will convert a PDF file to HTML5 using Java but now it
will also compress any .png images in the converted
output, thus reducing file-size!!

14. Follow us
www.idrsolutions.com
http://blog.idrsolutions.com
With thanks to the author:
Nathan Howard