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I would like to interrupt rsync with ctrl-c (let's say after half the file has transferred) and resume without having to resend the data that has already been transferred.

The stackexchange/google information I have found seems conflicting. I found some some who say use --partial and some who say use --append. To me it sounds like they both would work.

If I want to interrupt rsync with ctrl-c, should I use --partial or --append?

If both would work, when is it better to use one vs the other?

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2 Answers 2

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To restart, --partial is sufficient. Use --inplace if you really don't want rsync to create a temporary file that merges the existing copied data and the new, for example if rsync will have permissions issues creating a temporary file in the target folder.

Only use --append if you can guarantee that the partially copied data is still identical to the source. (Generally this is a false optimisation.)

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  • 1
    so when i use the above options (actually using --append-verify) and rsync still claims it is starting from the beginning, and I don't see any change in the file-size and the remaining file time is what it originally was when I started the copy, is rsync lying, or should I be worried?
    – Michael
    May 21, 2016 at 7:27
  • @Michael if you have a local source and destination all the rules change.
    – Chris Davies
    May 21, 2016 at 10:48
  • I was doing it across the LAN, but after a bit more experimenting, it appears that the issue is that since --append-verify actually has to actually read the parts of the file on both sides that are there, t isn't any faster due to the bottleneck being an older drive on the read side and not the LAN itself.
    – Michael
    May 21, 2016 at 15:41
  • @Michael well yes, if you've asked for verification of the data already transmitted then it has to read the data!
    – Chris Davies
    May 21, 2016 at 16:05
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    @alper I've never noticed that option before. It looks like it would be best to use --partial-dir, but I've not yet tried it.
    – Chris Davies
    Oct 15, 2018 at 9:40
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  • --append presumes the file may already exist in the destination, it just makes rsync not check the content already there (but see below).
  • --partial tells rsync to not delete partially transferred files.

You'll also need --inplace with --partial (it is implied with --append).

Turns out --inplace actually implies --partial, this is why --append is enough (it implies --inplace which implies --partial). But --partial alone is not enough, you need --inplace, otherwise rsync creates temp files instead of updating the final one.

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  • If I want to interrupt rsync with ctrl-c, I would use --append? Because --partial by itself would not resume.
    – Trevor Boyd Smith
    May 13, 2015 at 10:57
  • I'd use just --inplace. rsync "always resumes" (it tries to transfer the minimal data needed). What --append does is tell rsync to not checksum the data already at the destination, so if the partial file at the destination has been corrupted, it will stay corrupted with --append. --append might be interesting if, say, the partial file is very large and you can't wait (and is sure or don't care if it's corrupted), or some other specific situation.
    – spuk
    May 13, 2015 at 11:54
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    on Fedora 20 man rsync the option --append says ... Implies --inplace
    – Trevor Boyd Smith
    May 13, 2015 at 12:25
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    --inplace will work. --append will work because (as I stated in the answer) it implies --inplace, which implies --partial (which will keep partially transferred files when interrupted by Ctrl-c, which was the original question). So --append means "do as --inplace, but don't checksum what's already in the destination. It is an important difference. If you don't care about it, use either.
    – spuk
    May 13, 2015 at 12:38
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    so then what's the point of --partial WITHOUT --inplace
    – Evan Carroll
    Mar 17, 2017 at 20:17

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