Listing 1

This one usually works.  It correctly determines if
/etc/cron is running.

ps -fu root | grep /etc/cron

root  641    1 0 22:23:00   ?    0:00 /etc/cron

This one never works.  The sleep 2 simulates a heavily
loaded system, causing grep always to find at least
one "/etc/cron" in the ps output.

( sleep 2 ; ps -fu root ) | grep /etc/cron

root  641    1 0 22:23:00   ?    0:00 /etc/cron
root  221    1 0 22:36:25  01    0:00 grep /etc/cron