I have also been doing more work on being cross-platform. The experimental command-line unar tool from earlier is now much improved. It actually takes some arguments now, for one. There is also a new too, lsar, for listing the contents of archives.

Both are still far from feature-complete. Most obviously, unar has no way to automatically contain unpacked files in a directory like The Unarchiver does, and it also overwrites files without asking, so be careful with that. lsar also does not show very much information about the files it lists, either.

Precompiled binaries for OS X and Windows are avaiable:

http://theunarchiver.googlecode.com/files/unar0.2.zip
http://theunarchiver.googlecode.com/files/unar0.2_win.zip

The Windows version requires a couple DLLs which are included. I hope to cut down on those later on.

For Linux, you will need to build it yourself. I have only tested this on Ubuntu so far. For a stock Ubuntu system, what you need to do after downloading and unpacking the source is:

sudo apt-get install build-essential
sudo apt-get install libz-dev
sudo apt-get install libbz2-dev
sudo apt-get install libssl-dev
sudo apt-get install libgnustep-base-dev
sudo apt-get install libicu-dev
cd XADMaster
make -f Makefile.linux

This should give you the unar and lsar executable, along with some test programs.

I'd really appreciate it if people could take the time to test these tools on various systems, and report any problems or requests!