Cut white margins in a pdf.

Very usefull tool on ubuntu: pdfcrop
http://manpages.ubuntu.com/manpages/gutsy/man1/pdfcrop.1.html

Example

                pdfcrop --margins 10 input.pdf output.pdf
 
               pdfcrop --margins ’5 10 5 20’ --clip input.pdf output.pdf

Hard Drive Utilities

Tool for testing the drive (just an informative tool but complete, it does not repair)
Smartmontools: Tool for analyzing the state of your hard drive:
https://help.ubuntu.com/community/Smartmontools


Install it by doing:

1) sudo apt-get install smartmontools 

2) If you want, add a graphical interface:

sudo apt-get install smartmontools

3) Run some tests, there are three types 

1. Short
2. Extended (Long)
3. Conveyance

A complete information of your hard drive can be obtained from: 

    sudo smartctl -a /dev/sda   

Repairing bad sectors 

A tutorial on how to repair bad sectors:  

http://zerinsakech.com/2011/04/20/how-to-repair-bad-sectors-on-hard-drive/

To repair a ext4 filesystem, use:

$  fsck.ext4  -fp

-p    is used to indicate automatic repair (no questions)

-f    is used to force checking even if filesystem is marked clean 

-c is also usefull when in order to make a read-only scan to find bad blocks and add them 

   to the badblock list to avoid using it in the future

if your system is ext2 or ext3, you can use the option "-C 0" or "-C 1" respectively to show 

a progress bar.