$ strace -fe execve perl -e '$code=system("ps > /dev/null;exit 3"); print("Finished with $? (or ",$?>>8,") $code (or ",$code>>8,")\n");'
execve("/usr/bin/perl", ["perl", "-e", "$code=system(\"ps > /dev/null;exi"...], [/* 51 vars */]) = 0
strace: Process 24618 attached
[pid 24618] execve("/bin/sh", ["sh", "-c", "ps > /dev/null;exit 3"], [/* 51 vars */]) = 0
strace: Process 24619 attached
[pid 24619] execve("/bin/ps", ["ps"], [/* 51 vars */]) = 0
[pid 24619] +++ exited with 0 +++
[pid 24618] --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=24619, si_uid=1000, si_status=0, si_utime=0, si_stime=1} ---
[pid 24618] +++ exited with 3 +++
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=24618, si_uid=1000, si_status=3, si_utime=0, si_stime=0} ---
Finished with 768 (or 3) 768 (or 3)
+++ exited with 0 +++