Where sa-update Keeps the Latest Rules

When fighting spam, I like to know that
I"m working with the latest rules. The
sa-update command is fairly quiet
about what it is doing. I tend to run
sa-update and then wonder if anything
happened.

Here's where sa-update keeps the most
up-to-date rules on my system:

/var/lib/spamassassin/3.003001/updates_spamassassin_org/

In time, the version number, 3.003001, will be outdated.
This page tells you why:

Rule Updates

The timestamps on all the files in the above directory are the
same. All the timestamps are identical and just a few minutes
old.

As of this writing, it appears that sa-update updates
all the files in the directory by overwriting them. This
makes sense. Since all these files appear to be small text
files, perhaps this is as good an approach as any.

To observe sa-update in action, you might try this
command. The command includes the -D switch which
gives debug information:

sa-update -D

I had assumed that my rules were updated each time I retrieve
email with Kmail. I'm wrong! Does this mean I should
run sa-update just before I retrieve email? Perhaps so.

Also, I notice that I have to run sa-update as root or it does
not work. This makes sense.

Will I get less spam if I run sa-update more often? I'm
going to experiment to see.

Update: January 11, 2012

I'm back trying to fill in the holes in my knowledge
about sa-update. A question I've had all along
is Does sa-update automatically update?.

Apparently not. It's apparent to me that in my current
Linux distribution, which is Debian Squeeze, sa-update
is a manual operation. I'm guessing that there is a way
to make it automatic, I just don't personally know how to
do it.

In reading the sa-update man page, I find that
there are 2 fundamental truths regarding the availability
of updates:

1. If you run sa-update and no update is available,
   sa-update exits with an exit status of 1
2. When an update does become available, running
   sa-update will give you an exit state of 0

So it all comes down to one or zero. So that's how
this thing works! I've been wondering about this
for quite some time.

In ancient times, when I was still writing Unix
shell scripts regularly, I knew that typing
echo $? at the command line prompt would
give you the exit status of the last command
typed.

Try this command sequence:

ls
echo $?
ls --invalidoption
echo $?

The first command, ls, gives you an exit
status of zero. The second command, ls --invalidoption,
gives you an exit status of something other than
zero.

Zero is OK and non-zero is not so OK.

Apparently this is how you determine whether or not
sa-update has an update for you. You type the following
2 commands:

1. sa-update --checkonly
2. echo $?

If the exit status is a zero, an update is available.
IF the exit status is one, no update is available.

I think I've finally figured out how to tell whether
or not sa-update actually did something. Run
sa-update and check the exit status before and
after.

If the exit status is zero before you run sa-update
and it is non-zero after you run sa-update, sa-update
actually did something.

Got it!

The lesson here seems to be if you dig deep enough, you
find the answer you are looking for.

Ed Abbott