1. A system call tracer. strace is a system call tracer, i.e. a debugging tool which prints out a trace of all the system calls made by a another process/program. The program to be traced need not be recompiled for this, so you can use it on binaries for which you don't have source. System calls and signals are events that happen at the user/kernel interface. A close examination of this boundary is very useful for bug isolation, sanity checking and attempting to capture race conditions. From Debian 3.0r0 APT

2. The strace program intercepts and records the system calls called and received by a running process. Strace can print a record ofeach system call, its arguments and its return value. Strace is useful for diagnosing problems and debugging, as well as for instructional purposes. Install strace if you need a tool to track the system calls made and received by a process. From Mandrake 9.0 RPM

3. trace system calls and signals From whatis