Rm does not permanently delete files

#1

Post by harshasrinivas » Thu, May 19, 2016, 12:30 PM UTC

Rm does not permanently delete files
medium.com

Re: Rm does not permanently delete files

#2

Post by gjvc » Thu, May 19, 2016, 12:47 PM UTC

Re: Rm does not permanently delete files

#3

Post by notanote » Thu, May 19, 2016, 1:18 PM UTC

If I've understood correctly when I read about this before, programs that overwrite before unlinking do not work for an SSD. The SSD probably will not write the data to the same location as the old file. Instead, use fstrim to have the disk reclaim all free space. After that it's supposed to be impossible to recover.

https://en.m.wikipedia.org/wiki/Trim_(computing)

Re: Rm does not permanently delete files

#4

Post by brudgers » Thu, May 19, 2016, 1:29 PM UTC

Defaulting to "rm -rf *" makes me imagine what could possibly go wrong.

Re: Rm does not permanently delete files

#5

Post by pubby » Thu, May 19, 2016, 1:34 PM UTC

This is the type of program that should be written in C, not in Javascript with 9 different dependencies...

Re: Rm does not permanently delete files

#6

Post by throwaway7767 » Thu, May 19, 2016, 1:44 PM UTC

This functionality already exists in GNU coreutils, it's done by the shred(1) command. No need to install any extra third-party software, shred is already installed.

Also, as another commenter already pointed out, this kind of in-place overwrite is not guaranteed to work on SSDs, and it's also not guaranteed to work on filesystems with copy-on-write semantics. If you're really concerned with this, you should be doing full-disk encryption.

Re: Rm does not permanently delete files

#7

Post by [deleted] » Thu, May 19, 2016, 1:48 PM UTC

[deleted]

Re: Rm does not permanently delete files

#8

Post by Rubu » Thu, May 19, 2016, 1:51 PM UTC

brudgers wrote: post #4

Defaulting to "rm -rf *" makes me imagine what could possibly go wrong.

Pretty sure that was just an example to demonstrate that skrub uses the -rf options by default.

Re: Rm does not permanently delete files

#9

Post by wiredfool » Thu, May 19, 2016, 1:54 PM UTC

throwaway7767 wrote: post #6

This functionality already exists in GNU coreutils, it's done by the shred(1) command. No need to install any extra third-party software, shred is already installed. Also, as another commenter already pointed out, this kind of in-place overwrite is not guaranteed to work on SSDs, and it's also not guaranteed to work on filesystems with copy-on-write semantics. If you're really concerned with this, you should be doing…

Looking at man shred, apparently one can shred stdout.

Re: Rm does not permanently delete files

#10

Post by masklinn » Thu, May 19, 2016, 1:55 PM UTC

throwaway7767 wrote: post #6

This functionality already exists in GNU coreutils, it's done by the shred(1) command. No need to install any extra third-party software, shred is already installed. Also, as another commenter already pointed out, this kind of in-place overwrite is not guaranteed to work on SSDs, and it's also not guaranteed to work on filesystems with copy-on-write semantics. If you're really concerned with this, you should be doing…

> This functionality already exists in GNU coreutils, it's done by the shred(1) command. No need to install any extra third-party software, shred is already installed.

That's only true for GNU-based userlands, not BSD-based ones.

> Also, as another commenter already pointed out, this kind of in-place overwrite is not guaranteed to work on SSDs

And if the system properly TRIMs it might not be necessary at all, though that greatly depends on the SSD.