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Comment by dspillett | Hacker News Reader

> Need to get a file from one box to another? Have SSH? `scp` is your friend

For less trivial transfers (recursive structures, large collections that you want to sync with minimal time) rsync supports SSH as a transport medium out of the box so

    scp remote.host:path.txt local
    scp local remote.host:path

becomes

    rsync remote.host:path.txt local
    rsync local remote.host:path

for the basics, then start adding the other options that you need:

    rsync some/local/dir me@remote.host:/target/ --recursive --times
    rsync some/local/dir me@remote.host:/target/ --archive # archive does recursive and also preserves times, ownership, etc.
    rsync some/local/dir me@remote.host:/target/ --recursive --delete-before --dry-run
    … … …

In fact, I usually end up using rsync even for the basics, just out of habit typing that instead of scp.

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I must admit my rsync experience is limited. I do not know the behaviors and flags very deeply. It's on my list though, as it's surely another one of those foundational linux tools. I know it is even faster than cp on the same host for some situations.

rsync is the tar of network transfers. It is extremely useful, but has too many options, so one ends up memorizing a few use cases and carefully sticking to them.

I still have PTSD from the time I played with the options and made the mistake of swapping source and destination, where the destination was a blank disk.

haha, you say rsync is the tar of network transfers, but have you ever considered using tar for network transfers?

Time a 'tar | nc' sometime to a remove server, it'll blow away the rsync time.

you are not wrong, but you are missing the argument

--dry-run is a useful safety net when trying new combinations of options. That, and the fact it'll never delete unless you specifically give it an option with "delete" in its name.

In my experience, rsync is a tool that's worth it despite not knowing most of what it can do. I use `-a` to get the behavior you want (which is superset of a bunch of options like preserving filesystem permissions, copying recursively, and other things I haven't bothered to memorize) `--info=progress3` to show progress/network speed updating on a single line (no idea what the other progress options do, but this one does what I want), and if I'm transferring something that's not already compressed, I use `-z --compress-choice=zstd`. After those flags, it's basically a drop-in replacement for scp (`remote:srcpath dstpath` for copying to local and `srcpath remote:dstpath` for copying to remote).

The basics for just copying files as you would with scp are pretty intuitive:

    rsync source destination

    rsync source destination --recursive

with the only extra gotcha being that you need to be careful whether you need trailing /s on directories (sometimes where CP or scp would complain and exit, rsync will do something that isn't quite what you intended).

The first complication you might hit is when you want to sync, including deleting files at the destination as needed, rather than just copying. This isn't _that_ complicated really, but caution is understandable because mistakes can cause unintended deletions. The --dry-run and verbose output options are your friend here, and the assurance that it won't delete anything unless you explicitly give it one if the --delete* options.

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