PDF password recovery free

There is always this password, this pdf, being secured by you. In fact too secured that you can never remember the password. Instead of move the PDF to trash there some way to recover the password.

There are a bunch of PDF password recovery/cracking software charging a few to tens of dollars. While in the wonderful work of Unix/Linux you, this kind of tool is free. There is one that I found recently:


To install, on Ubuntu

sudo apt-get install pdfcrack

on OS X, install brew and:

brew install pdfcrack

You will be prompt to enter password to install the tool

To start the recovery, simply:

pdfcrack "/usr/jonsnow/Download/birthcert.pdf"

To save use control-C to exit the tool, the tool will attempt to save.

The recovery process may takes hours to days depends on the security setting of the PDF. You will be prompted with the recovered password in command prompt upon succeed.


Let me know if it saved your day 🙂

* Be sure you have the right to perform recovery, i.e. you own the file but forget the password. Any wrong doing will still be wrong doing, so don’t do it.

* For Windows users, make friend with unix/linux people. They are like dentists, scary but really helpful.

pdfcrack [Official link]


[Latex] Remove “Cited by” from bib


Sometimes .bib generated contains useless contents which make their way to your references, see Figure 1. you cloud have 10 or 300 citations depend on the article that you are working on. Here how to clean it up in a few key strokes.



Figure 1, some .bib generated include “cite by …”




Make a copy of your .bib file. Get sublime -> use replace function -> enable regular express as shown in Figure 2. – > use regular express:

.* \{cited by.*

.* means to match anything, so this regular express match anything before an after “{cited by”.

Replace it with nothing.

  • You can search to see if the replacing is what you expected before actually hitting the replace button. See Figure 2.


Make good use of Sublime


Figure 2, enable, use regular expression search in Sublime 2


Figure 3 shown the result. Just do the compilation normally and it is all cleanup.



Figure 3, cleaned up 🙂


Other thoughts

  • alternatively, a shell script can be written to do the something, but sublime works on Linux, OS X and Windows.
  • this trick can be used for other unwanted content in .bib or even for other type of file.
  • remember  to make a copy of the original file before you make the changes.