Fix #427: add strace -f option

README.md

@@ -319,7 +319,7 @@ mkdir empty && rsync -r --delete empty/ some-dir && rmdir some-dir
 
 - For more serious network debugging, [`wireshark`](https://wireshark.org/), [`tshark`](https://www.wireshark.org/docs/wsug_html_chunked/AppToolstshark.html), or [`ngrep`](http://ngrep.sourceforge.net/).
 
-- Know about `strace` and `ltrace`. These can be helpful if a program is failing, hanging, or crashing, and you don't know why, or if you want to get a general idea of performance. Note the profiling option (`-c`), and the ability to attach to a running process (`-p`).
+- Know about `strace` and `ltrace`. These can be helpful if a program is failing, hanging, or crashing, and you don't know why, or if you want to get a general idea of performance. Note the profiling option (`-c`), and the ability to attach to a running process (`-p`). Use trace child option (`-f`) to avoid missing important calls.
 
 - Know about `ldd` to check shared libraries etc.