Using `rsync` as more advanced `cp`

homebrewmergersync

For copying large files (and/or large quantities of files), especially across disks, I prefer to avoid using the Finder as it often fails with some meaningless error message and/or complaint about permissions.

Instead I have been looking at using rsync — or, more specifically, the latest version of rsync available from Homebrew, which, as of today, is:

rsync  version 3.1.1  protocol version 31

Capabilities:
64-bit files, 64-bit inums, 64-bit timestamps, 64-bit long ints,
socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
append, ACLs, xattrs, iconv, symtimes, no prealloc, file-flags

(Those are the default capabilities that Homebrew uses.)

The problem is that rsync is hopelessly complex, and I'm never sure if I am using the proper arguments, or if there are others that I should be using:

rsync \
    --8-bit-output \
    --acls \
    --backup \
    --devices \
    --exclude='.DS_Store' \
    --executability \
    --group \
    --human-readable \
    --inplace \
    --itemize-changes \
    --owner \
    --perms \
    --progress \
    --prune-empty-dirs \
    --recursive \
    --safe-links \
    --specials \
    --stats \
    --times \
    --update \
    --verbose \
    --xattrs \
    'foo' /path/to/destination/

Args I'm not sure if I should be using or not, mostly because I'm not 100% sure what they do:

  • (one of the other options for links instead of '–safe-links')
  • –relative
  • –sparse
  • –partial

Any other suggestions?

Best Answer

Unless you have some specific needs, I would throw out most of those options and keep it simple: rysnc -aEv (on the default OS X version) or rsync -aXv (on the Homebrew version).

Options

  • -a is archive mode, which essentially means preserve the metadata (timestamps, permissions, etc.) and do a recursive copy. This is what you want for your standard backup or copy operations.

  • -E/-X preserves extended attributes (a.k.a. resource forks). In the past the built-in rsync version had special functionality to cover HFS+ quirks in this regard, but newer default versions of rsync may be improved in that regard now. I would lean towards using the built-in version unless you have a specific reason not to.

  • -v is the verbose option, and simply makes it easier to track what's going on if you're running this in a Terminal window. If it's going to be running in a script, you can remove it.

Unless you know you need them, you can safely ignore most of those options you've got already. Some are duplicated by the archive command, and others (like --inplace, which can slow things down and leave the filesystem in an inconsistent state) are only necessary for specific edge cases. Do yourself a favour and keep things simple — if you run into specific issues with the options I've listed, perhaps enumerate those (in a separate question if need be).

As an aside, running into problems copying via Finder is a bit of a red flag IMO. While it may not always be as fast as some options, it shouldn't be throwing error messages. You may want to verify/repair your disk in Disk Utility.

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