Here's a preliminary port of strace to FreeBSD.

Here are some notes about it :

- This couldn't have been done without the sources of the truss
  utility by Sean Eric Fagan, which were of great help.
  
- The tracing mecanism used by FreeBD is a lot like the SVR4 one, so
  this port shares a lot of code with the SVR4 port, including the
  akward event loop when tracing multiple processes.

- This works for i386 binaries, although support for alpha processor
  should be quite straight forward, but I do not have an alpha to
  test it on.

- Tracing linux binaries is not supported yet, but should be possible
  with some work.
  
- There are some issues with following forks, and only a few FreeBSD
  specific syscalls are decoded right now.

- This was tested on FreeBSD 4.0. I believe the tracing interface is
  present since at least FreeBSD 3.0, so it "should" work on all
  latest releases. I have no idea for other BSDs, though.
  
Gaël Roualland <gael.roualland@iname.com>