Sunday, 15 January 2012

Converting PDF Files To Text Or HTML From Linux Terminal

Earlier, we saw how we can merge or combine PDF files from terminal. Now, I am sharing two command line tools to convert PDF files to text or html files.

Poppler Utils is a great package of PDF rendering and conversion tools and should be installed before we convert PDF files to text or html files. You can install the poppler-utils issuing the following command in debian based distro. You can install them in your favorite distros using their corresponding package installers.

sudo apt-get install poppler-utils

Now that poppler-utils is installed, we will be able to convert PDF files to text and HTML using pdftotext and pdftohtml command-line tools.

PDF to Text


To convert a PDF files to text, we should use pdftotext command. Following is the simplest form of the command for converting a PDF file to text file.

pdftotext file.pdf file.txt

This command also allows you to preserve the original layout in the pdf file using the -layout switch as below:

pdftotext -layout file.pdf file.txt

Similarly, if you wish to convert pages of specific range, you can use -f and -l switches to specify the first and last page to convert to text file. An example below would clarify things where I've choosen to convert pages from 4 to 8 into text.

pdftotext -f 4 -l 8 file.pdf file.txt

Check the man page of pdftotext and also see the help for the tool to explore other options as well.

PDF to HTML


To convert a PDF file to HTML file, you can use the pdftohtml tool available in the poppler package. Before that, I will show how to use pdftotext command to convert the PDF file to HTML file.

pdftotext -f 4 -l 8 -htmlmeta file.pdf file.html

Now, using the pdftohtml tool is not that different than pdftotext. A simplest form would be as below:

pdftohtml file.pdf file.html

You can use the same arguments as in the pdftotext for this tool as well for specifying the range. However, -htmlmeta and -layout are only available in pdftotext. I would let you explore more on the pdftohtml tool.

I hope this information is useful for you. :)

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Merge/Combine PDF Documents In Linux From Terminal

Hi everybody, I was inactive for a while due to some health problems(chronic sinusitis, to be specific) and would like to apologize for not writing. This time, I am writing about how you can easily combine pdf files into a single pdf file using a linux terminal.

pdftk is a small but powerful handy PDF manipulation tool with many useful features to work with PDF files. The MAN page for pdftk says, "If PDF is electronic paper, then pdftk is an electronic staple-remover, hole-punch, binder, secret-decoder-ring, and X-Ray-glasses. Pdftk is a simple tool for doing everyday things with PDF documents."
You can use it to:

* Merge PDF Documents or Collate PDF Page Scans
* Split PDF Pages into a New Document
* Rotate PDF Documents or Pages
* Decrypt Input as Necessary (Password Required)
* Encrypt Output as Desired
* Fill PDF Forms with X/FDF Data and/or Flatten Forms
* Generate FDF Data Stencils from PDF Forms
* Apply a Background Watermark or a Foreground Stamp
* Report PDF Metrics such as Metadata and Bookmarks
* Update PDF Metadata
* Attach Files to PDF Pages or the PDF Document
* Unpack PDF Attachments
* Burst a PDF Document into Single Pages
* Uncompress and Re-Compress Page Streams
* Repair Corrupted PDF (Where Possible)

Today I'll show you how to combine or merge two or more pdf documents to a single PDF document using this tool. Navigate to the folder containing the PDFs you want to merge and then type the following command:

pdftk *.pdf cat output outputfile.pdf

The above command will take the PDF files in the alphabetical order and if you want to have your own order of the PDFs, say for an example, I have two PDFs a.pdf and b.pdf and I want pages from b.pdf to appear before a.pdf then I would simply do:

pdftk b.pdf a.pdf cat output outputfile.pdf

The pdftk is not limited to this simple merging method only, it has very powerful capabilities for merging documents. Below is an example of how I merged page 1-5 of first pdf and 10-15 of another pdf.

pdftk A=a.pdf B=b.pdf cat A1-5 B10-15 output outputfile.pdf

Below example shows how I can merge even pages from first pdf and odd pages from second pdf.

pdftk A=a.pdf B=b.pdf cat Aeven Bodd output outputfile.pdf

You can make numerous other variations and looking the MAN page for pdftk would be a good idea to explore more options. So why would we need heavy graphics based PDF editor when things can be done by a small commandline utility like pdftk.

I hope this post is useful to you. :)


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Saturday, 31 December 2011

Details On The CON Issue In Windows

We can not create a folder with its name as "Con" in windows and many people are unaware of this fact and the reason behind this. So I am here to clarify everything about the CON issue in windows. I will also discuss about the way to create such folders in windows.

If you haven't tried yet, try creating the folder with the name con and you will find that the folder can not be renamed to con. This is not the only name that shows such unique behavior. Other such names that can not be the name of folders are CON, PRN, AUX, CLOCK$, NUL, COM0, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT0, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9(list taken from Wikipedia).

These words are the reserved words and date back to old MS-DOS days. These names were reserved for MS-DOS device files and hence to prevent any kind of ambiguity, these names are not allowed for normal files and folders.

But there's way. Now comes the role of Universal Naming Convention(or Uniform Naming Convention) commonly known as UNC which specifies a common syntax to describe the location of a network resource, such as a shared file, directory, or printer.

The UNC syntax for windows system is as below:

\\ComputerName\SharedFolder\Resource

You can read about UNC in the wikipedia entry.

UNC was introduced after the introduction of MS-DOS so MS-DOS systems do not understand the UNC naming i.e. it is not backward compatible to MS-DOS. That said, we can create folders with special names in our local system using the UNC syntax. The single dot (.) is used to indicate the local system as per the UNC definition.

Now to create a folder with any of the reserved words, we will use mkdir command. For example, to create a CON folder in my friend's laptop's Desktop folder, I typed the following command in the command prompt.

mkdir \\.\C:\Users\suman\Desktop\con

This creates a con folder in our desktop. Now try to delete it using GUI or from command prompt by issuing rmdir con command. It will give you an error. So to delete the folder, you can use the same UNC syntax as below:

rmdir \\.\C:\Users\suman\Desktop\con

On issuing this command, your con folder should be gone. You can try the same with the other reserved file names. Also, check the following screenshots for clarity.




Some of you might think Whats the use of all this stuff?: I don't know if there's any serious use of this stuff but its kinda cool to know these kind of stuffs for tech-freaks. If there can be any good use of this trick, please share over here. I hope this stuff is useful. Happy New Year 2012 :)


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Friday, 30 December 2011

Download Your Facebook Information [How To]

Well you might want to download your facebook information as an offline archive just like you would like to have backup of your other information. In this How To, I am sharing a helpful information on how you can backup your facebook information easily.

You can download following information from your facebook profile.
- Any photos or videos you've shared on Facebook
- Your Wall posts, messages and chat conversations
- Your friends' names and some of their email addresses

1) Login to your facebook account.

2) Click on Account option on the right top corner of your facebook page and then click on Account Settings from the dropdown menu.




3) Now click on the Download a copy link.





4) On the next page, click on the Start My Archive button.




5) A new pop-up will appear and again click on the Start My Archive button from the pop-up.




6) You will receive an email when your archive is ready for download. This may take some time. You can check your inbox later to view and download the archive containing your facebook information.

For more information about downloading information, check the Facebook Help page.

I hope it becomes useful for you. :)


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[FIX] Android XML Layout and Resource Design View Not Working In Eclipse

Hi sometimes XML views for your layouts and resources such as strings do not appear in the design view and you might be getting frustrated why this is happening. This post mentions a quick tip on how you can regain your original XML layout and/or resource design views.

The trick is simple. All you have to do is right click the layout or resource file in the "Package explorer" and then use the option "Open With" to open the file with the correct editor. In case of XML layouts, choose the Layout Editor option and in case of XML resources like strings, choose the Resource Editor option. Eclipse automatically saves your last choice so everything should work fine after doing these steps. I hope it comes useful sometimes. :)


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Thursday, 29 December 2011

How To Get Timeline In Your Facebook Profile

Earlier, many people were wondering how can they get timeline for their facebook page when they were helping us with votes in the library so I thought why not make a blog post so that it would help people out there to get the timeline feature in their profile.

What is timeline?: Who would better explain than facebook itself regarding its feature... Read about timeline.

Now to get timeline, go to Introducing Timeline page and if you are not already using timeline, a bottom footer will appear with the Get Timeline button at the right side.





All you have to do is click on that link to get timeline for your facebook. Timeline will be activated and you will be redirected to your timeline. I hope this helps you. :)


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Wednesday, 28 December 2011

Adding Regular User To Sudoers File In Linux

Hi everybody, this time I am writing about the different command line methods of adding regular user to the sudoers file in linux or in more obvious way, giving access to root privilege to certain regular users. The sudoers file(located at /etc/sudoers by default[in my distro i.e. ubuntu]) contains the information of groups and users who can execute commands with root privilege. I'll list 3 ways of adding users to the sudoers list so continue reading the post.

Method 1
The first way is to use the usermod command to append the user to the admin group. Since the admin group has the privilege of executing commands with sudo privilege, adding the user to the admin group is one easy way to add regular user to the sudoers file. The example command is as below(Replace user with the proper username which you want to add to sudoers list):

sudo usermod -a -G admin user

Method 2
This method is similar as above however the command is adduser this time and the command is even more simpler to remember. Just specify the respective user to be added to the admin group as below:

sudo adduser user admin

Method 3
The last method I'm writing about is the safe way of editing sudoers files. Linux advises to use visudo command to edit /etc/sudoers so that possible errors while writing in sudoers file can be avoided. Typing just visudo would open the /etc/sudoers file for editing, and in case, if you want to edit sudoer file in alternate location, type visudo -f sudoer_with_path. Anyway, to add new user to the default sudoers file, type sudo visudo and add the line as below(Replace user with the proper username to whom you want to give sudo privilege) at the end of file:

user ALL = (ALL) ALL

I hope these methods come useful for you.


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Saturday, 24 December 2011

Hiding Information In Text Files Using Notepad [Windows]

Hi everybody, I had long ago read about hiding information inside text files using notepad and today I suddenly remembered while doing some other task. So I am sharing this little trick of hiding information inside the text file using notepad.

Open command prompt (Run-> Cmd) and then navigate to the directory (using cd command) where you want to save your text file. Now, type the following command:

notepad file.txt:mypassword


Replace filename part and password with yours as shown in the screenshot above and then you will be asked if you wish to create a new file or not(See the screenshot below) and then click on Yes to create the file.



Now enter your secret information in the file and save the file. Close the file and if you need to access the contents later, you will have to use the exact command you used while creating the file. If you or someone else edits your file without giving the password, your original hidden content will not be erased and you can still access the content with your original command.

I hope this trick is new for you. :)


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