Spelunking the places where files are not

Tor Arntsen kspt.tor at gmail.com
Mon Mar 8 03:16:20 CST 2021

On Fri, 5 Mar 2021 at 15:41, John Foust via cctalk
<cctalk at classiccmp.org> wrote:
> After thinking about disk imaging tools like Greaseweasel,
> I started thinking about tools that would grab and examine the unused
> portions of disks.
> It's obviously file-system dependent.  At one level we know of
> "undelete" tools that could piece together recently deleted files
> and restore them intact by using abandoned bits of block table info.
> Of course some simple file systems can't even permit that.

Linux distros come with a standard tool to do some of that,
'testdisk'. From the overview:

"Partition scanner and disk recovery tool"

 It works with :
  * DOS/Windows FAT12, FAT16 and FAT32
  * NTFS ( Windows NT/2K/XP )
  * Linux Ext2 and Ext3
  * BeFS ( BeOS )
  * BSD disklabel ( FreeBSD/OpenBSD/NetBSD )
  * CramFS (Compressed File System)
  * HFS and HFS+, Hierarchical File System
  * JFS, IBM's Journaled File System
  * Linux Raid
  * Linux Swap (versions 1 and 2)
  * LVM and LVM2, Linux Logical Volume Manager
  * Netware NSS
  * ReiserFS 3.5 and 3.6
  * Sun Solaris i386 disklabel
  * UFS and UFS2 (Sun/BSD/...)
  * XFS, SGI's Journaled File System
 PhotoRec is file data recovery software designed to recover
 lost pictures from digital camera memory or even Hard Disks.
 It has been extended to search also for non audio/video headers.
 It searches for following files and is able to undelete them:
  * Sun/NeXT audio data (.au)
  * RIFF audio/video (.avi/.wav)
  * BMP bitmap (.bmp)
  * bzip2 compressed data (.bz2)
  * Source code written in C (.c)
  * Canon Raw picture (.crw)
  * Canon catalog (.ctg)
  * FAT subdirectory
  * Microsoft Office Document (.doc)
  * Nikon dsc (.dsc)
  * HTML page (.html)
  * JPEG picture (.jpg)
  * MOV video (.mov)
  * MP3 audio (MPEG ADTS, layer III, v1) (.mp3)
  * Moving Picture Experts Group video (.mpg)
  * Minolta Raw picture (.mrw)
  * Olympus Raw Format picture (.orf)
  * Portable Document Format (.pdf)
  * Perl script (.pl)
  * Portable Network Graphics (.png)
  * Raw Fujifilm picture (.raf)
  * Contax picture (.raw)
  * Rollei picture (.rdc)
  * Rich Text Format (.rtf)
  * Shell script (.sh)
  * Tar archive (.tar )
  * Tag Image File Format (.tiff)
  * Microsoft ASF (.wma)
  * Sigma/Foveon X3 raw picture (.x3f)
  * zip archive (.zip)

I haven't used the tool recently, but some ten-fifteen years ago there
was for some reason much more disk trouble and I used the tool
effectively to recover lost data and partitions.

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