Two-way directory syncer

Usually, I sync files between two sites using the standard rsync -a and/or scp -p approach. However, this is very cumbersome and error prone if changes have been carried out on both sides: For each directory (or even file) that has been touched on either side, it has to be determined in advance which side should take precedence (e.g. by a preliminary dry-run and manual inspection).

syncd will ease the task of recursively merging two directories with each having independent changes: For each file or directory with different attributes (permissions, timestamps, existence, … – but no content checksum), a proposed bi-directional resolution strategy is derived. The user can then choose to accept, skip, or provide a custom action for each found difference interactively.

Merging directories: usage

The only mandatory arguments are the directories to work on. Their order is only relevant in presence of other arguments that refer to a specific side (a or b suffix):

syncd [--delete-excluded[-a|-b]] [--keep-(a|b)] [--dry-run] [--backup[-a|-b]=dirname] a/ b/

--dry-run

Will show what changes would have been proposed, but without actually doing anything. Afterwards, you can select to re-run with automatically performing all changes, but I am not confident enough to recommend this.

--keep-(a|b)

Will selectively prevent changes to either side.

--backup[-a|-b]

Creates the respective directory name relative to the directory to sync and moves into it instead of deleting or replacing, s.t. file contents won’t be lost.

--delete-excluded[-a|-b]

Per default, several file-/dir-names will be (silently) skipped, e.g. *.o or .git. (There is currently no way to provide custom exclusions – please edit the list in the code if needed.) Giving this option will ask for deletion on both or either sides instead.

Warning: This tool was built for (and tested with) only certain scenarios. There are still many things to be done regarding error recovery, atomicity, and correctness/robustness in general. Use only interactively, offline, and with caution!

To build locally, simply type make. No special dependencies or additional external libraries are needed. System-wide installation is not required but make install will (build and) copy the binary into the system. make uninstall will remove it again.