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[[!meta title="Securely deleting files and clean diskspace"]]
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Why use secure deletion?
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**Operating systems do not actually remove the contents of a file when it is
deleted**, even after emptying the trash or explicitly removing the file, from
the command line for example.
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Instead, they simply remove the file's entry from the file system directory, because this requires less work and is therefore faster. The contents of the file—the actual data—remain on the storage medium. The data will remain there until the operating system reuses the space for new data.
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Likewise, reformatting, repartitioning or reimaging a system is not always guaranteed to write to every area of the disk, though all will cause the disk to appear empty or, in the case of reimaging, empty except for the files present in the image, to most software.
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Finally, even when the storage medium is overwritten, physical properties of the medium might make it possible to recover the previous contents. In most cases however, this recovery is not possible by just reading from the storage device in the usual way, but requires using laboratory techniques such as disassembling the device and directly accessing/reading from its components.
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To learn more, see the Wikipedia article on [[!wikipedia Data_erasure desc="data erasure"]].
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<a id="usb_and_ssd"></a>
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Warning about USB sticks and solid-state disks
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The only way to securely delete any data, even a single file, from a USB stick or an SSD (Solid-State Disk) is to [[securely erase the entire device|secure_deletion#erase-device]].
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For more details read the corresponding section of the Wikipedia article on [[!wikipedia Data_erasure#Limitations desc="data erasure"]].
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Securely delete files
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<p>Securely deleting files does not erase the potential backup copies of
the file (for example LibreOffice creates backup copies that allow
you to recover your work in case LibreOffice stops responding).</p>
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Navigate to the folder containing the files that you want to delete.
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Select the files that you want to delete with the mouse.
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Right-click (on Mac, click with two fingers) on the files and choose <span class="guimenuitem">Wipe</span>.
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Confirm.
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1. The deletion will start. It can last from a few seconds to several minutes,
according to the size of the files. Be patient…
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<a id="clean_disk_space"></a>
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Securely clean available disk space
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