Scalpel is a fast file carver that reads a database of header and footer definitions and extracts matching files from a set of image files or raw device files. Scalpel is filesystem-independent and will carve files from FATx, NTFS, ext2/3, or raw partitions. It is useful for both digital forensics investigation and file recovery.
This article explain how to use scalpel to recover deleted files.
on a debian or ubuntu install scalpel.

$ sudo aptitude install scalpel

In the config file scalpel.conf you have to define some file types that scalpel will search, in our example we will check for pdf files, so we uncomment these lines:

$ sudo vi /etc/scalpel/scalpel.conf

[...]
pdf y 5000000 %PDF %EOF\x0d REVERSE
pdf y 5000000 %PDF %EOF\x0a REVERSE
[...]
First of all make sure that the output directory does not exist, so to recover data from the sda1 partition, we can use scalpel as following:

$ sudo scalpel /dev/sda1 -o output

And the result is stored into the output directory with a full audit file.