#!/bin/bash

# example of simple incremental / full backup script

# 1-6000 second random delay (prevents all student virtual hosts from taking backups simultaneously)
# uncomment these two lines before implementing to the server with crontab scheduler:

#mydelay=$(shuf -i 1-6000 -n 1)
#sleep $mydelay

# testing and creating backup directories
if [ ! -e /mnt/backup/ ]; then mkdir /mnt/backup; fi
if [ ! -e /mnt/backup/increment ]; then mkdir /mnt/backup/increment; fi
if [ ! -e /mnt/backup/full ]; then mkdir /mnt/backup/full; fi

# filesize set to unlimited and default file permissions
ulimit -f unlimited
umask 066

# setting locations of individual backups
DATA1="/etc"
DATA2="/usr/local"
DATA3="/home"
LIST=$(mktemp) # temporary filename for filename list(s)
set $(date) # date output will go to $1, $2 etc

# Full backups if Sunday
if test "$1" = "Sun" ; then
tar cfz "/mnt/backup/full/full_backup_etc.tar.gz" $DATA1 >& /dev/null
tar cfz "/mnt/backup/full/full_backup_usr_local.tar.gz" $DATA2 >& /dev/null
tar cfz "/mnt/backup/full/full_backup_home.tar.gz" $DATA3 >& /dev/null
rm -f /mnt/backup/increment/increment*

else

# Incremental backups if not Sunday: Backup new or within 1 day modified files
# Find locates the files and tar creates the backup archive

find $DATA1 -depth -type f \( -ctime -1 -o -mtime -1 \) -print > $LIST
tar cfzT "/mnt/backup/increment/increment_etc_$6-$2-$3.tar.gz" "$LIST" >& /dev/null

find $DATA2 -depth -type f \( -ctime -1 -o -mtime -1 \) -print > $LIST
tar cfzT "/mnt/backup/increment/increment_usr_local_$6-$2-$3.tar.gz" "$LIST" >& /dev/null

find $DATA3 -depth -type f \( -ctime -1 -o -mtime -1 \) -print > $LIST
tar cfzT "/mnt/backup/increment/increment_home_$6-$2-$3.tar.gz" "$LIST" >& /dev/null

rm -f "$LIST" # deleting the temporary file before exit
fi