FreeBSD is a UNIX-like operating system that is similar to Linux, but has a different aim in terms of licensing and documentation.
The Arduino software can be built on FreeBSD as a port.
To install the port, log in as root or use su(1) to switch to the root user. Then cd to the Arduino port directory, build, and install the port:
# cd /usr/ports/devel/arduino # make install clean
Any additional ports that are needed by the Arduino port will be automatically downloaded and installed. You may have to answer some configuration option screens during this process. The best way to do that is by accepting the defaults.
For more information, see the FreeBSD Handbook.
After the port has been installed, an entry will be added to the desktop Development menu. Start the Arduino software from there, or run arduino from the shell.
I would like to add my ten cents' worth, based on my own experiences using FreeBSD 7.3 and 8.1 and the Arduino Uno.
With the Uno it has an additional ATMel 8u2 microcontroller doing the USB in lieu of an FTDI chip. As such, it more closely follows the ACM spec (normally used by USB modems) but is not always compatible with any of FreeBSD's USB serial drivers. Fortunately I have written one that appears to work properly, which is now a part of the ports collection as 'comms/uarduno'.
A link to a web site with the driver and information is here: http://mrp3.com/uarduno.html
Additional information is also available for some of the newer USB identifiers, and I'll add more (and update the port) as they are made available to me.
As of the January 2012 ports collection, it appears that earlier IDE and configuration issues that I had reported here are now resolved, and I have been using the 1.0 IDE for Arduino development environment under FreeBSD 8.3 (stable) with unmodified versions of rxtx and avrdude, so it's all working well (thanks to developers and port maintainers for assistance in getting issues resolved). Additionally, starting with version 8.2, it appears that the ACM driver may also work with the newer Arduino and MEGA2560 boards (R3), although your mileage may vary. But if your board isn't recognized, or the serial interface doesn't function, you can always install comms/uarduno .
bobf at mrp3 dot com