> Strace can only trace one manually selected process or process tree.
You can ask strace to attach as many processes with "-p" as you want.
What it doesn't support is both running a process and attaching to processes (some Idi^Hmisguided person filed a bug about that to Debian and they "fixed" it by removing this functionality that's mentioned even in strace manual page. I have a bug of it in Debian).