#!/bin/sh -p
#
# monthly_alias
#
# AUTHOR:
#   Dan Harkless                                                    <opensource@
#   http://harkless.org/dan/software/                              harkless.org>
# 
# COPYRIGHT:
#   This file is Copyright (C) 1997 by Dan Harkless, and is released under the
#   GNU General Public License <http://www.gnu.org/copyleft/gpl.html>.
#
# USAGE:
#   % monthly_alias <monthly_email_prefix> <forward_to_account>
#
# EXAMPLE:
#   % monthly_alias dan dan-pop
#   % tail -1 /etc/aliases
#   dan_jan97: dan-pop
#
# DESCRIPTION:
#   Adds an alias to the /etc/aliases file of the form $1_mmmyy.  Mail to that
#   address will be forwarded to $2.  You might set up a cron job to do this at
#   midnight on the 1st of every month.
#
#   These monthly aliases are useful when posting to Usenet expecting replies.
#   People can email you without having to go through any anti-SPAM contortions,
#   yet you can stave off the flow of SPAM at the end of the month, or once
#   you've got all the replies you need.
#
#   On normal systems, this script will have to be setuid root to be able to
#   write to /etc/aliases.  On Solaris, the "-p" parameter to /bin/sh preserves
#   the effective uid and gid rather than resetting them to the real uid and gid
#   values.  Before installing monthly_alias, make sure that the /bin/sh on your
#   system does not allow the caller to craft $1 or $2 to be able to execute
#   arbitrary commands as root by embedding " and ; characters (I should really
#   re-write this as a perl script with taint checks).
#
# DATE        MODIFICATION
# ==========  ==================================================================
# 1997-01-07  Original.

# Make sure 2 parameters were passed.
if [ $# != 2 ]; then
  progname=monthly_alias  # can't use $0 in a setuid script on Solaris
  echo "usage: $progname <monthly_email_prefix> <forward_to_account>"
  exit 1
fi

# Get the date in mmmyy format.
mmmyy=`date +%h%y | tr "[A-Z]" "[a-z]"`

# Add an alias to /etc/aliases.
echo "$1_$mmmyy: $2" >> /etc/aliases