Translated into Czech: https://www.zoobio.se/teaching/2017/06/22/co-je-zfilter/
ZFilter is an e-mail filtering program. Like a real filter (say, for
coffee), ZFilter can strain out some unwanted or unpleasant e-mail, or
working in reverse, can allow you to only receive mail from certain other
people.
If that was all it did, it wouldn't be especially unique, or anything
for me to really brag about. Fortunately it isn't. ZFilter is capable
of taking a wide range of actions to a much wider range of situations.
ZFilter can run other programs, send form responses, forward mail to
other people and maintain a variable set and counters that let you
easily keep track of how much mail you have received, and from whom.
ZFilter can print summaries, showing you how often each action you told
it to take was used and how much mail you have received from each e-mail
address. It can even detect chain letters in a lot of cases (about
95% of the time) and let you delete them automatically, or send a prepared
nasty-gram back to whoever sent it to you.
ZFilter is designed to make the old "/bin/filter" that comes with ELM
obsolete. It (hopefully) provides a superset of the commands available
to the old filter, and is more flexible and versatile in different
situations.
ZFilter can be found wherever your favorite archives of
comp.sources.unix are stored. It is occasionally posted to
comp.lang.perl.misc (about once every two versions or so).
It is available on CPAN in the directory /authors/Steve_Zeck
(for a random site, go to http://www.perl.com/CPAN/authors/Steve_Zeck )
It is also on my home page at http://www.guam.net/home/viper/files.html
and is (as a last resort) available uuencoded via eMail if you send a
message to viper@kuentos.guam.net with the words "send zfilter" in the
subject line of the message.
Support from the author can be obtained by e-mailing
saintly@innocent.com
Ideas and suggestions are always welcome.
Flames are welcome, just put the word "FLAME" in the subject line. :)
1.1 Why should I use it?
Do you get junk mail? Is someone harrasing you and you don't want
their mail? Want saved copies of mail from certain people? Want all
your mail forwarded to another site, and a message sent to people who
use your old address to use the new one? Wish you could auto-acknowledge
mail from people who worry too much? Have any use for a primitive
Listserver? Wanna look cool to all your computer-techie friends? Would
you like to keep logs of who writes to you the most and how much mail
you receive every day? Hate chain letters? Would you like to send
personalized mail to groups of people who write to you and look sincere
and understanding before you've even read it? Enjoy looking at other
people's source code?
ZFilter is capable of responding to nearly any situation you might run
into with mail, especially if you use external programs to cover wierd
specific ones.
One copy of ZFilter can serve a system. All users may configure it
differently for their needs. A restricted filter (rzfilter) is available
for systems that would like to provide a filter to their users, but don't
want users to be able to run other programs (through pipes). It is more
secure and limits what people can do to get around your internal security
if you're using rksh or other restricted-shell. It is available upon
request from the author.
1.2. Who is this document intended for?
Although I wanted to include lots of technical information about ZFilter
for the variety of UNIX-savvy dudes out there, I realized that one of the
problems with the old filter and why it wasn't as widely used as it could
have been was that the average user with shell access to an ISP couldn't
figure out how to set it up or get it working from the man page or some
of the other help files for it. This document _tries_ to explain both
the technical stuff that experienced and froody UNIX dudes want to know,
but it also tries really hard to make it so that inexperienced UNIX newbies
can figure out how to get it going themselves. In doing so, I hope rather
than be annoyed at having to wade through stuff they already know, the
coolest of the cool Unix dudes will bear with me and skim to the things
they _do_ want to know.
What should you read?
Newbies: Read _everything_. I'm not kidding. I'm not going to answer
any questions if the answer is plain-as-day in this doc. If
you don't understand something, it probably isn't important
right now.
Unix Hacks: Skim "variables" to see how ZFilter extracts variables from
message headers. Look at the extra variables ZFilter gets from
your environment and the "ones you shouldn't change".
You should be familiar with most of the operators, but I've
introduced "?" and "#" as regex pattern-matches. Go see the
end of the operators section and the Misc. section.
You'll want to read all the commands available, you may want to
glance at the examples of commands to see ZFilter syntax in
action. Other than that, you may want to skim the rest at your
leisure. Zfilter should understand the old-style filter rules
files, but you may find that some things you did with the old
filter can be done with fewer lines or more efficiently with
ZFilter's new commands and abilities.
People upgrading from an old ZFilter: Go to the very end of this message
and read the modification history to see what has been changed
from your version of ZFilter. Changes, new commands, etc.. should
be documented in the appropriate places.
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