Program on Linux (and maybe other flavours of UN*X?) to run a command, logging all syscalls and signals. This is an incredibly useful tool sometimes, but you always need to grep the output to find what you're looking for.

Applications include:

If you're afraid of that last application, don't delete strace! Your problem isn't there, it's in the kernel hooks which let the program do its work! In other words, the bad guys can just bring their own version, while the good guys have been deprived of an important tool.

On most other UN*X systems, what is called strace does something else completely. On Solaris, Sun at least give you truss, which does what strace does.