sfill

Overwrite free space and inodes of a disk with 38 writes (slow but secure)

$ sfill [/path/to/mounted_disk_directory]

$ sfill -l -v [/path/to/mounted_disk_directory]

$ sfill -ll -v [/path/to/mounted_disk_directory]

$ sfill -I [/path/to/mounted_disk_directory]

$ sfill -i [/path/to/mounted_disk_directory]

sfill [-lviz] [-m ] [-s ]

-l
    List all mount points and exit.

-v
    Verbose mode. Displays more information during the wipe process.

-i
    Interactive mode. Prompts for confirmation before starting the wipe.

-z
    Wipe the free space with zeros after all other wipe passes have been completed.

-m
    Specify the mount point of the partition to wipe. If not specified, sfill will attempt to wipe the free space on the current directory.

-s
    Sets the number of over-writes. Default is 3.
The security level specifies how many times the free space will be overwritten. A higher security level increases the difficulty of data recovery but also increases the wipe time.

sfill is a utility that securely wipes all the free space on a specified partition. It repeatedly overwrites the free space with random data, making it extremely difficult, if not impossible, to recover any previously deleted files or data that might have resided there. This is crucial for maintaining data privacy and security, especially before disposing of a hard drive or re-purposing a partition. sfill offers multiple wipe passes with different patterns to increase the security of the wipe. Note that this process can be time consuming, especially on large partitions.

sfill only wipes the *free* space on a partition. It does not delete existing files. If you need to securely erase individual files, use the 'shred' command.
sfill's effectiveness relies on the underlying filesystem implementation. Some advanced filesystems with features like copy-on-write may make complete data erasure more difficult.
Running sfill on an SSD drive can significantly reduce its lifespan due to the increased number of write cycles. SSDs have limited write endurance, so use this command with caution.
This program is considered obsolete. Use `wipefs` or `shred`.

While sfill attempts to securely wipe data, there is no guarantee that data will be completely unrecoverable. Advanced forensic techniques might still be able to recover fragments of data, especially if the drive has suffered physical damage or if the filesystem uses advanced features. Use it as a measure, but for highly sensitive data destruction, physical destruction of the drive is often the only completely secure option.

shred(1), wipefs(8)