System call tracing tool for general Unix binaries.
This is a tool that comes with your operating system. If it is not called strace, it may be called truss instead. It is NOT written in Tcl - just a tool that often helps in tracking down problems.
[RJ - Actually, strace is in fact also a debugging command in TCL. You can use the TCL exec to get the OS version of strace.] - RS: Well, you can use any executable with exec that is on your $PATH...
See also: ktrace
AMG: A classmate of mine referred to strace as "the king of Unix commands."