6. How do I automate the connection procedure?

Automated handling of news and email is quite easy to implement in Linux.

First and foremost one should make a /usr/lib/ppp/ppp-on that initiates the ISP connection. Often, this file will simply contain the following:

/usr/sbin/pppd

connect "/usr/lib/ppp/chat -v -f /etc/ppp/chatscript"
crtscts
modem
defaultroute
asyncmap 00000000
user dirk
/dev/modem 38400

To end a connection, use the supplied version of /usr/lib/ppp/ppp-off.

Having tested the functionality of these two scripts, one must then write scripts that perform the various tasks. The script to collect email has been described before, and we will here assume it is located at /home/dirk/pop.

A script for exchange of email can then be produced in /root/mail:

#! /bin/sh
#
# exchange mail
# 10 minutes timeout:
TIMEOUT=600
DT=10

# kick sendmail:
sendmail -q &

# retrieve mail:
su dirk -c /home/dirk/pop

# wait for sendmail to terminate:
t=0
while ! mailq | grep -q "Mail queue is empty"; do
    t=$[$t+$DT]
    if [ $t -gt $TIMEOUT ] ; then
     echo "sendmail -q timeout ($TIMEOUT).."
     exit 1
    fi
    sleep $DT
done

exit 0

The script to exchange news may be placed in /usr/lib/news/news:

#!/bin/sh
#
# exchange news
# must be run as news:
cd /usr/lib/news

#update the outgoing batch (C News):
/usr/lib/newsbin/input/newsrun < /dev/null

#exchange news:
/usr/lib/newsbin/newsx acme news.acme.xz

#and flush the incoming batch:
/usr/lib/newsbin/input/newsrun < /dev/null

#!/bin/sh
#
# exchange news and email
# must be run as root
#
if ! /usr/lib/ppp/ppp-on; then
    exit 1
fi
trap "/usr/lib/ppp/ppp-off" 1 2 3 15

#exchange news+mail:
/root/mail &
su news -c ~news/news
wait

#disconnect..
/usr/lib/ppp/ppp-off

#update the incoming batch (C News):
su news -c /usr/lib/newsbin/input/newsrun < /dev/null &

exit 0

It is quite easy to make an extension to the above that only will establish a connection if outgoing email and news is present. Lets call it /root/news+mail.cond, and keep in mind that the name of the outgoing news-spool must be updated to suit:

#!/bin/sh
#
# exchange news and email, only if outgoing news or mail
# (C News spool)
if [ -s /var/spool/news/out.going/acme/togo ] ||
    ! ( mailq | grep -q "Mail queue is empty"); then
     /root/news+mail
fi

The only thing remaining is to specify when all this is going to happen. This is done using the command crontab -e as root. Let us assume that we always want to exchange news and mail at 07:00 in the morning, and after that every 4th hour assuming there are outgoing email and news:

00 7            * * *   /root/news+mail
00 11,15,19,23  * * *   /root/news+mail.cond

ALT: Depending on ones preferences, it is also possible to turn the process upside down. Every time a PPP link is initiated, the script /etc/ppp/ip-up will be started. One may here add whatever magic is required to start exchange of email and news. See man pppd for further detail.

ALT: It is also possible to automatically connect PPP whenever network traffic is detected. This is in many ways the more elegant solution, but it is quite dependent on a good configuration to avoid frequent (and costly) connections being made. More information can be found at:

http://www.dna.lth.se/~erics/diald.html

The diald utility is available from:

ftp://sunsite.unc.edu/pub/Linux/system/network/serial/diald-0.16.tar.gz

At the same location one will also find other variations on the theme PPP connections.