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15 questions linked to/from Clear unused space with zeros (ext3,ext4)
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3 votes
1 answer
4k views

If I dd my disk and compress the image with lzma or lzo the image is still big. The partition is 10GB used, 90GB available. But the image still around 20GB. I believe that is because I have copied ...
Diogo Melo's user avatar
  • 153
24 votes
5 answers
12k views

I have 200 GB free disk space, 16 GB of RAM (of which ~1 GB is occupied by the desktop and kernel) and 6 GB of swap. I have a 240 GB external SSD, with 70 GB used1 and the rest free, which I need to ...
cat's user avatar
  • 3,538
56 votes
1 answer
35k views

I tried to cat /dev/zero, and it didn't seem to do anything. I googled /dev/zero, and it says it's basically a blank file with infinite size. Is cat printing an infinite number of non-existent ...
tkbx's user avatar
  • 11.5k
8 votes
7 answers
7k views

the zerofree command finds the unallocated, non-zeroed blocks in an ext2 or ext3 file-system and fills them with zeroes A NTFS Windows machine, with a mechanical drive, was upgraded from 7 to 10. ...
gatorback's user avatar
  • 1,532
18 votes
3 answers
1k views

I know that most files, when deleted, aren't actually removed from the disk, and can be recovered later. How can I ensure that a directory I had deleted will actually be removed from the disk? Are ...
jcora's user avatar
  • 3,874
12 votes
3 answers
14k views

How to clear unused space with zeros ? (I am asking for tool for btrfs filesystem) I'm looking for something smarter than cat /dev/zero > /mnt/X/big_zero ; sync; rm /mnt/X/big_zero Like ...
Grzegorz Wierzowiecki's user avatar
  • 14.8k
3 votes
4 answers
1k views

is there a command on Linux to remove a file but zeroing it's contents first? so if i do, something like this: rm -rf /var/cache/pacman/pkg/* it would overwrite each file on that directory with 0 ...
Kokizzu's user avatar
  • 10.6k
12 votes
1 answer
4k views

From reading this, it seems that when copying data to a different hard drive, cat automatically uses the optimum block size (or very near it). I wonder how it determines the optimum block size, and ...
EmmaV's user avatar
  • 4,417
7 votes
1 answer
6k views

I deleted a file I meant to shred first. $ rm somefile instead of $ shred somefile $ rm somefile Is there a way to shred a file after 'rm'-ing it?
Drist's user avatar
  • 173
5 votes
3 answers
4k views

How do I securely delete a folder, with all of its contents, so it cannot be recovered? I have tried the shred command but it only works with files and not folders. I have also found out that there ...
Sillo's user avatar
  • 51
3 votes
2 answers
2k views

I currently have an unencrypted external hard drive that I use as a backup for my encrypted (with LUKS) main machine. To update my backup, I simply log in to the main machine and rsync to my external ...
J. Mini's user avatar
  • 127
3 votes
1 answer
4k views

I have just created an image of an sd card using dd and the image is compressing down less than expected. I suspect this is because the card had not been zeroed out before I started to make the image. ...
Nick's user avatar
  • 31
1 vote
1 answer
2k views

For security reasons I want to wipe the unused disk space on my storage media. How do I do that? In other words, I want my unused disk space to be replaced with zeroes.
Sir Muffington's user avatar
  • 1,306
0 votes
1 answer
326 views

Basically I didn't encrypt my Linux (Debian) partition when installing it. However I found a way to encrypt at least home folder so in theory I could put everything there which I want to make sure it'...
dragonmnl's user avatar
  • 2,429
2 votes
1 answer
359 views

For backup reasons I need to use dd to copy a whole hard drive (including MBR, partitions,...). The hard drive is 80 GB in size where only 1.8 GB are used. The command I'm using is the following: dd ...
Thomas's user avatar
  • 153