System Trace is a tool for hackers.
Say you have some python application such as [[Reposurgeon]] that you need to understand better. You can attach <code>strace</code> to the <code><abbrev abbr title="process id">pid</abbrevabbr></code> of the running application to see the underlying system calls being made.
<source lang="bash">
sudo strace -f -s128 -e trace=open -p$(ps -o lwp= -LC python2 | tail -1)