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I want a command to shred completely the contents of a folder/directory (which may be inside folders/directories). Also please explain the command.

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Define "shred". If you just mean what the shred command does, then there's your answer. – psusi Apr 16 '12 at 13:17
    
Very closely related: askubuntu.com/questions/57572/… – Takkat Apr 16 '12 at 13:41
    
@psusi- by shred i mean delete file beyond recovery. i was using the shred command but as that was applicable only to files i wanted a similar command to delete folders and files within it. – Ashu Apr 16 '12 at 14:30
    
Which one does the job perfectly shred or secure-delete? – Ashu Apr 16 '12 at 14:32
    
both of the solutions work for me but i think the srm one is easier. – Ashu Apr 18 '12 at 17:00
up vote 17 down vote accepted
  1. Install the package 'secure-delete'
  2. Use the command 'srm -r pathname' to remove your folder and files

The default settings are for 38 (!!!) passes of overwrites which is extreme overkill imho (see more info about this here: http://www.anti-forensics.com/disk-wiping-one-pass-is-enough.

For my usage, I only want a single pass of random data so I use 'srm -rfll pathname'

If you want to create a right-click option in the GUI for files and folders, use gnome-actions to call a script like this:

#!/bin/bash
if dialog=`zenity --window-icon=warning --question --title="Secure Delete" --no-wrap --text="Are you sure you want to securely delete:\n\n     $1\n\nand any other files and folders selected? File data will be overwritten and cannot be recovered."` 
then /usr/bin/srm -fllrv "$@"| zenity --progress --pulsate --text="File deletion in progress..." --title="Secure Delete" --auto-close
fi 

If you want more paranoid settings be sure to modify the above script.

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1  
-f fast (and insecure mode): no /dev/urandom, no synchronize mode. -l lessens the security (use twice for total insecure mode). could you please explain these two things. 38 overwrites is default how do these affect the '38' value. and why l two times in -rfll – Ashu Apr 16 '12 at 14:57
2  
OK, the whole default process is: 1 pass with 0xff (a zero wipe), 5 random passes with /dev/urandom is used for a secure RNG if available, 27 passes with special values defined by Peter Gutmann, another 5 random passes from /dev/random. Then rename the file to a random value & truncate the file. IIRC, /dev/random is considered a better random number generation system. Using -fll we skip the 1+5+27+5 passes and substitute with a single pass of random data, possibly from a less "truly random" generator. – Veazer Apr 16 '12 at 18:16

For files not directories, here's a more simple way instead of -exec shred -u {} \; type of way:

cd to your directory.

then

find -iname "*" -type f | xargs shred -fuzv -n 48

this does 48 passes recursively to the current directory you cd'ed into.

Hope this helps some.

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Adding '-print0' to find and '-0' to xargs? Directories may have whitespace in their names. – weakish Jul 27 '13 at 15:03
    
Good answer but Why do you use xargs?? I don't understand xargs. – Creator Sep 11 '15 at 5:40

Shred works only on files. You need to shred the files in the dir/subdirs first and then remove the directories. try

find [PATH_TO_DIR] 

and make sure you only see the files you want to delete

find [PATH_TO_DIR] -exec shred -u {} \;

then remove the dirs with

rm -rf [PATH_TO_DIR]
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can u please explain {} \; . also somewhere elsi i had seen the same command as your but it was '{}' \; what is the difference between the two?? – Ashu Apr 16 '12 at 14:43
    
Since shred doesn't work on directories, how about adding the option -type f to the find commands? – andol Apr 16 '12 at 15:49
    
@ andol : yeah i was thinking of that.. – Ashu Apr 16 '12 at 18:35
    
Cant explain it any better than the find man page .... the {} and \; are part of the -exec option of the find. – Ruediger Apr 16 '12 at 20:03

You probably want to use something similar to this:

find dir -type f -exec shred -fuz {} +
rm -rf dir

First command finds only files and passes them to shred (as many at once as possible - no need to start a new shred process for every file like \; does). Finally, remove the directories too.

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When I need to shred multiple files or an entire directory I simply use shred -vzn 20 ./shredme/*.* for example, which overwrites all files with any file extension in the "shredme" folder. Then you can use the standard rm -rf ./shredme command to remove the folder itself (or just right click and delete the folder) as all the data has been overwritten 20 times for this example.

I did a quick example of this with a bunch of duplicate images as an example.

Terminal screenshot

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