I found this piece of code in /etc/cron.daily/apf
/etc/apf/apf -f >> /dev/null 2>&1
/etc/apf/apf -s >> /dev/null 2>&1
>> /dev/null 2>&1
>> /dev/null redirects standard output (
/dev/null, which discards it.
>> seems sort of superfluous, since
>> means append while
> means truncate and write, and either appending to or writing to
/dev/null has the same net effect. I usually just use
> for that reason.)
2>&1 redirects standard error (
2) to standard output (
1), which then discards it as well since standard output has already been redirected.