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Photorec

Recover lost files from harddisk, digital camera and cdrom.

dd

Convert and copy a file - block level - warning: also known as 'data destroyer.

fdisk

Manipulate disk partition table.

Recuva

Recover your deleted files quickly and easily.

hdparm

Get/set SATA/IDE device parameters.

ncdu

Provides a fast and easy-to-use interface through famous du utility.

Fio

Flexible I/O Tester.

Testdisk

Checks the partition and boot sectors of your disks. It is very useful in recovering lost partitions.

Wipe

The wipe command can be used to securely erase files from magnetic media.