I'd just downloaded a file named pdfcrack-0.11.tar.gz from internet. i untar it in folder home/etc and then run the command "make" in directory home/etc/pdfcrack-0.11. it runs fine and no error has been given or such. an object file is created along with executable file in my defined directory.
now i wana open a .pdf file that is password protected. how to do it?

and the fact about password protected file is that i don't know the password

cracking passwords is against the forum rules

we can not help you in possibly breaking the law

there is no default folder called /home/etc

it is not in the system $PATH unless you manually added this odd location

have you even bothered to read the instructions on the program website ??????
http://pdfcrack.sourceforge.net/

also it is a VERY OLD and out of date and never to be updated program
it was last updated in 2008 -- 6 YEARS AGO -- with most of the code from 2006 ( 8 YEARS AGO )
one full computer generation ago ( well 1.5 generations ago )

from reading the README and code it looks like it only works on the 8 year old version of md5

please use current and still supported software

this project died back in 2008

The forum rules do not permit posts with legally dubious activities. Closed.