Wait for defunct grand^n-child processes

[jhunt]

Found this today, from an experiment in Postfix + Dovecot:

→  ps -ef | grep 2534
root      2534  2516  0 Oct14 ?        00:00:17 /bin/init -L /dev/log -- postfix start-fg -- dovecot -F -- postgrey -q --inet=127.0.0.1:10023 --delay=60
root      2596  2534  0 Oct14 ?        00:00:05 /bin/init -L /dev/log -- postfix start-fg -- dovecot -F -- postgrey -q --inet=127.0.0.1:10023 --delay=60
root      2598  2534  0 Oct14 ?        00:00:27 /usr/sbin/dovecot -F
sshd      2599  2534  0 Oct14 ?        00:00:00 postgrey -q --inet=127.0.0.1:10023 --delay=60
syslog   20798  2534  0 16:56 ?        00:00:22 [smtpd] <defunct>
syslog   23548  2534  0 17:43 ?        00:00:20 [trivial-rewrite] <defunct>
syslog   24595  2534  0 18:00 ?        00:00:14 [qmgr] <defunct>
syslog   24777  2534  0 18:03 ?        00:00:13 [trivial-rewrite] <defunct>
syslog   25472  2534  0 18:17 ?        00:00:09 [pickup] <defunct>
syslog   25631  2534  0 18:20 ?        00:00:08 [anvil] <defunct>
root     25672  2534  0 18:20 ?        00:00:08 [smtpd] <defunct>
syslog   27521  2534  0 Oct14 ?        00:00:10 [tlsmgr] <defunct>
root     28031  2534  0 19:39 ?        00:00:00 /bin/sh /usr/lib/postfix/sbin/postfix-script start-fg
jhunt    30046 29795  0 19:57 pts/0    00:00:00 grep --color=auto 2534