#!/bin/bash
# rotate-user-maildrop-logs version 0.1
#  Copyright (c) 2009 Lamont R. Peterson <peregrine@openbrainstem.net>
#  P.O. Box 1043, Centerville, Utah, U.S.A.  84014-5043
# 
#  This program is free software.  You can redistribute it, or modify it,
#  or both, under the terms of the GNU General Public License version 3
#  (or any later version) as published by the Free Software Foundation.
# 
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
#  General Public License for more details.
# 
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see <URL:http://www.gnu.org/licenses>.

NUMBER_TO_KEEP="5"
GZIPPED=".gz" # Set to "" if you don't want the files gzipped, ".gz" if you do.

# Loop through all users who have a home directory under /home/.
for i in $(ls /home/); do
	# Does this user have a ~/.mail/.maildrop.log file?
	if [ -e /home/${i}/mail/.maildrop.log ]; then
		# Calculate the remailing space until the file will be "full".
		BYTES_UNTIL_FULL=$(echo "51200000 - $(ls -l /home/${i}/mail/.maildrop.log | sed 's/  */ /g' | cut -d" " -f5)" | bc -l)

		# Is the user's ~/mail/.maildrop.log file almost full?
		if [ "${BYTES_UNTIL_FULL}" -lt "51200" ]; then
			# Does a "too old to keep" file exist?
			if [ -e /home/${i}/mail/.maildrop.log.${NUMBER_TO_KEEP}${GZIPPED} ]; then
				# Remove oldest copy that should no longer be kept.
				rm /home/${i}/mail/.maildrop.log.${NUMBER_TO_KEEP}${GZIPPED}
			fi

			# Loop through any old copies from the limit number to 1.
			for j in $(seq $NUMBER_TO_KEEP -1 1); do
				# Does the old rotated file exist?
				if [ -e /home/${i}/mail/.maildrop.log.${j}${GZIPPED} ]; then
					# Rotate old copy.
					mv /home/${i}/mail/.maildrop.log.${j}${GZIPPED} /home/${i}/mail/.maildrop.log.$((${j} + 1))${GZIPPED}
				fi
			done

			# Rotate the nearly full file.
			mv /home/${i}/mail/.maildrop.log /home/${i}/mail/.maildrop.log.1

			# Are we gzipp'ing the rotated files?
			if [ "${GZIPPED}" = ".gz" ]; then
				gzip /home/${i}/mail/.maildrop.log.1
			fi

			# Create the proper new file.
			touch /home/${i}/mail/.maildrop.log
			chown ${i}. /home/${i}/mail/.maildrop.log
		fi
	fi
done