pipeto.sample

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#!/bin/rc

# create a /tmp for here documents
rfork en
bind -c /mail/tmp /tmp

KEY=whocares
USER=ken

RECIP=$1
MBOX=$2
PF=/mail/box/$USER/_pattern
TMP=/mail/tmp/mine.$pid
BIN=/bin/upas
D=/mail/fs/mbox/1

# save and parse the mail file
{sed '/^$/,$ s/^From / From /'; echo} > $TMP
upas/fs -f $TMP

# if we like the source
# or if the subject contains a valid token
# then deliver the mail and allow all the addresses
if( $BIN/list check $PF $D/from $D/sender $D/replyto )
{
	$BIN/deliver $RECIP $D/from $MBOX < $D/raw
	$BIN/list add $PF $D/from $D/to $D/cc $D/sender
	rm $TMP
	exit 0
}
switch($status){
case *!match*
	echo `{date} dropped $RECIP From `{cat $D/replyto} >> /mail/box/$USER/_bounced >[2] /dev/null
	rm $TMP
	exit 0
}
if ( $BIN/token $KEY $D/subject )
{
	$BIN/deliver $RECIP $D/from $MBOX < $D/raw
	$BIN/list add $PF $D/from $D/to $D/cc $D/sender
	rm $TMP
	echo `{date} added $RECIP From `{cat $D/replyto} \
		>> /mail/box/$USER/_bounced >[2] /dev/null
	exit 0
}

# don't recognize the sender so
# return the message with instructions
TOKEN=`{upas/token $KEY}
upasname=/dev/null
{{cat; cat $D/raw} | upas/send `{cat $D/replyto}}<<EOF
Subject: $USER's mail filter
I've been getting so much junk mail that I'm resorting to
a draconian mechanism to avoid the mail.  In order
to make sure that there's a real person sending mail, I'm
asking you to explicitly enable access.  To do that, send
mail to $USER at this domain with the token:
	$TOKEN
in the subject of your mail message.  After that, you
shouldn't get any bounces from me.  Sorry if this is
an inconvenience.

----------------
Original message
----------------
EOF

echo `{date} bounced $RECIP From `{cat $D/replyto} \
	>> /mail/box/$USER/_bounced >[2] /dev/null

rv=$status
rm $TMP
exit $status