Duet

Bi-directional synchronization, similar to unison. Maintains the last known state of two directories, identifies and synchronizes changes from that state.

Usage

USAGE:
    duet [FLAGS] <profile> [path]

FLAGS:
    -i, --interactive   interactive conflict resolution
    -y, --yes           assume yes (i.e., synchronize, if there are no conflicts)
    -b, --batch         run as a batch (abort on conflict)
    -f, --force         in batch mode, apply what's possible, even if there are conflicts
    -v, --verbose       verbose output
    -n, --dry-run       don't apply changes

        --version       prints version information
        --license       prints license information (including dependencies)
    -h, --help          prints help information

ARGS:
    <profile>    profile to synchronize
    <path>       path to synchronize

Profiles

Profiles are defined in ~/.config/duet/my_profile.prf and have the following structure:

~
ssh my_server duet ~

+Path1
+Path2
+Path3
-Path3/Path4
-Path3/Path5
+Path6

[ignore]
glob1*
glob2*

The first two lines specify the directories to synchronize. Either both are local, or the second one can have the form ssh server-name path/to/duet directory-to-synchronize. After a blank line, there is a list of inclusion-exclusion of paths under directory-to-synchronize (by default nothing is included). An optional [ignore] section specifies glob patterns to ignore.

Subsequently, duet my_profile will synchronize the two directories.

Caveat

Duet uses openssh crate, which only supports password-less authentication over SSH.

Comparison to Unison

Advantages of Unison:

• much more mature and battle-tested
• supports Windows
• provides GUI

Advantages of Duet:

• restricted synchronization
• interactive TUI

Restricted synchronization is perhaps the biggest advantage of Duet. Briefly, it's possible to restrict the directory scan to a specific path. Because the the scan typically dominates the running time, this can speed up the synchronization by two orders of magnitude, making this a major boost for certain workflows. It is possible to achieve something similar in Unison by creating several profiles that share the same state, but in practice it's much more convenient to not have to set these up for every project one wants to synchronize on demand.

The restricted path can be either absolute, or relative. In the former case, the base is automatically stripped. In the latter case, if the path starts with . or .., then it's relative to the current directory; otherwise it's relative to the base directory.

For example,

duet my_profile ~/Path1/...

duet my_profile .