pstack (print stack traces of running processes)

Outputs a backtrace for every thread in each requested PID.
Frame order within threads can be reversed.

This version of pstack is a bin/sh expect script which runs gdb. As
such, it should run on any platform which has expect and gdb installed.
To have expect on a Slackware system, you need to have installed the
tcl group (even if you are a Perl fanatic ;)