BTW simple text recovery from fdisk'd USB

As I was doing 'interesting' stuff with fdisk and master boot records 
trying to replicate what UNetbootin was doing for the bootable USB 
replication procedure in the last email,  I screwed up which USB disk 
was the source and which was the destination (and didn't notice for half 
an hour and about 10 fdisk committed changes).

Of course I had backups of most of the important files but not the 
documentation files I was writing up procedures in for others (and which 
I liberally copied from in the previous email) and of course the one 
script that I originally set out to create (the a script that copies MAC 
address info to a file.

As they were relatively small text files and I had a fair idea of what 
was in them I did the following:
1. Create a 8GB dd.img file (it was an 8GB USB):  sudo dd if=/dev/sdb 
of=dd.img (Could probably get away with not doing this but thought it 
was worth the extra 5-10 minutes)
2. Created a 160MB allstrings.txt file from the image: strings -ao 
dd.img >allstrings.txt (by default has all printable strings of 4 
characters and over which means it left out end-if statements in code on 
their own line i.e. 'fi' but thats the only thing I noticed was missing).
3. For each of the files I tried to come up with a string that was near 
the start of the file and nearly unique and then used grep on 
allstrings.txt to pull out the appropriate parts: grep -B 50 -A 150 
"string" > reasonablename.txt (finds the string and outputs the last 50 
and next 150 lines as well which ended up creating 3 or 4 1-10MB txt 
files - containing the correct text as probably around 5-10% of the 
bulk. I just pulled those numbers out of the air as definitely going to 
get the entire file)

I then just went and recreated the files from the appropriate portions. 
The strings command leaves a line number which I could have got rid by 
going into LibreOffice Calc and importing it as a space delimited file, 
deleted the first column and resaved. I was only looking for 3 or 4 
files with only a few score of lines in total so it wasn't worth it, I 
just manually went in and deleted extraneous lines and for the 
appropriate columns I deleted the line number as I categorised them.

-- 
"Believing men would act in their own interest was not cynicism, it turned out, but sheerest optimism; in reality men do not meet so high a standard."
-- Harry Potter and the Methods of Rationality (Chapter 84)
http://hpmor.com/

Reece Arnott
Dunedin
New Zealand


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