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I'm facing a problem with downloading zipped files from the Internet:

the problem is that when I download the file, in the directory "downloads" there are 2 files instead of one.

  1. First one is '' .tgz''
  2. the other one is '' .tgz.part''

and I'm pretty sure that is a download problem. Does anyone knows what this is about?

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    Yes, the .part indicates a partial download. It is about incomplete or failed downloads and it can have many causes.
    – user880592
    Jun 5, 2019 at 18:10

2 Answers 2

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No, that isn't a downloading problem. But rather that's how modern browsers/downloaders download files. Instead of downloading file in a single file, it downloads the file in some temporary files (.part in case of Firefox and Unconfirmed some_number.crdownload in case of Google Chrome). These temporary files can be single or multiple depending on the server it is connected to and the file size. These parts are generally done to establish multiple parallel connections from a single IP and improving the download speed.

Consider a file of 1GB is being downloaded. The server allows a maximum speed of 1MBPS. It would roughly take 1024 seconds to get downloaded. But if browser requests server for multiple connections to download a single and if server supports that, file could be downloaded in lesser time. Browser/Downloader will request server for downloading multiple files but with different starting and ending byte stream. This way the effective downloading speed is increased and you can enjoy the actual connection speed ISP provides.

Once downloading finishes, all part files are integrated into a single file and part files automatically gets deleted.

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    I'm not aware that any browsers use parallel streams for download by default?
    – vidarlo
    Jun 5, 2019 at 18:22
  • @vidarlo As far as I remember once I observed Chrome doing so.
    – Kulfy
    Jun 5, 2019 at 18:25
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    Interesting! I was not aware of that :) It appears to be controlled by chrome://flags/#enable-parallel-downloading
    – vidarlo
    Jun 5, 2019 at 18:26
  • @vidarlo Indeed. For firefox there's an extension
    – Kulfy
    Jun 5, 2019 at 18:32
  • That extension does not appear to use part files. From the description, "Make sure there is enough disk space. The files need to be first downloaded to Firefox's internal storage."
    – xiota
    Jun 5, 2019 at 18:57
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As noted by others, Firefox saves partial downloads to .part files. When the download is complete, the file is renamed. This is likely to prevent partial downloads from being mistaken for completed downloads. Other Mozilla-based browsers may use the same naming scheme. Chromium-based browsers appear to use a different extension (.crdownload).

It is not normal to have .part files left over after a download has completed. If you still have .part files, the download is either still in progress or incomplete. Check about:downloads in Firefox to see if they are still in progress.

In some cases, partial downloads can be resumed from within Firefox, but I have found it to be unreliable. External utilities are more reliable. For instance, wget and aria2c will resume incomplete files when the --continue flag is used. The output file should be set to the partially downloaded file. When the download is complete, you will need to manually rename it to remove the .part extension.

I have seen no evidence that any browser has ever used multiple .part files for multi-part downloads. Although there appears to be a Firefox extension that allows multipart downloading, the description states "Make sure there is enough disk space. The files need to be first downloaded to Firefox's internal storage." This internal storage indicates that the extension does not use multiple .part files.

External download utilities, such as aria2c, often preallocate disk space and index download allocation separately (sometimes within another file, but with a different extension, not .part).

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