Psync was written by Dan Kogai. Information on original version is here.

Psync is part of and requires MacOSX:File package. Source code is here (you have to build it).

If you prefer ready/prebuilt/binary package:
- for Panther just download and install this.
- for Jaguar: download and install this, then download my version of psync, and put it in /usr/local/bin.

If you already have a working version of MacOSX-File + psync and don't like installers, download psync, and put in /usr/local/bin.

Readme file is here.

If you use PsyncX, please note that it installs psync in /usr/bin (instead of /usr/local/bin). After installing PsyncX, copy or link psync from /usr/local/bin to /usr/bin.

If you use PsyncX, please note that it installs psync in /usr/bin (instead of /usr/local/bin). After installing PsyncX, copy or link psync from /usr/local/bin to /usr/bin.

Note: These installers are not compatible with Leopard or Snow Leopard. For a copy of psync compatible with Leopard/Snow Leopard, install excellent DejaVu (I am not related).
Even better, learn to use rsync. Version 3 is finally usable on Mac and in some cases, like copying to another Mac, may be better than Finder (because of AFP limitations and Finder design, files copied to a remote volume in Finder have their create/mod dates changed, so you cannot use that for incremental backups).
This is how I use rsync, to backup a folder to my wife's iMac:
rsync306 -vaAXNhPi --del --rsync-path="sudo /usr/local/bin/rsync306"' local-folder eli-imac.local:/Users/Shared/macpro-backup
For this to work you have to have rsync 3.0.6 installed in your PATH, another copy installed on remote machine in /usr/local/bin and have your name in sudoers.