in reply to Re: (OT) Logging open calls from a C program (system call tracing tools)
in thread (OT) Logging open calls from a C program
ktrace is also used on OpenBSD. Check for it on other BSD platforms if you happen to be use one.
Solaris 10 has a new tool called dtrace but as far as I know truss still works.
Update: You might also be able to use a debugger like gdb but I would use one of the tracing tools.