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I am trying to delete a file in linux, (Ubuntu 20.04). As per my understanding, when we delete a file, the inode and directory entry structures are modified first and the file is actually deleted at a later time. This is one of the reasons why the file can be recovered by different tools later.

I want to delete a file and know that it has been physically deleted from the disk. There should be no way that I can retrieve it at any point of time.

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  • shred is your friend
    – Panki
    Jul 7, 2020 at 15:13
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    @Panki not on an SSD it's not. Wear levelling may mean new sectors get allocated rather than old ones being overwritten
    – roaima
    Jul 7, 2020 at 15:18
  • Looking at the "caution" section in man shred, it also doesn't promise to work with journaling filesystems, which is… pretty much all of them, these days? I guess you could delete the file and then dd if=/dev/random of=fillthedisk; rm fillthedist which should fill most space available to files, likely including the old file contents, with randomness. Jul 7, 2020 at 15:47
  • This can be done with BleachBit. $ bleachbit --shred /path/to/file
    – KGIII
    Jul 7, 2020 at 16:33
  • Rather than shred the whole empty area of the disk, you might just find the block count of the file and use dd -i /dev/zero to kill the data before you rm it. Not sure why random junk is any harder to recover the data from than zeroes. Special care may be needed for huge sparse files. Jul 7, 2020 at 16:57

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