Simple Incremental Backups using rsync.

backup.sh

#!/bin/bash
unset PATH

#
# VARIABLES
#
BACKUP_DIR='/path/to/backup/location'                       # The backup directory
SOURCE_LOC=('/path/to/backup1' '/path/to/files/to/backup')  # The source backup
SOURCE_DIR=('backup1' 'backup2')                            # The directory name in backup for SOURCE_LOC
EXCLUDE=()                                                  # Directories to exclude

#
# BINARY VARIABLES
#
RSYNC=/usr/bin/rsync
CP=/bin/cp
MKDIR=/bin/mkdir
LOGGER=/usr/bin/logger

#
# DATE VARIABLES
#
YEAR=`/bin/date +%Y`
MONTH=`/bin/date +%m`
DAY=`/bin/date +%d`
YESTERDAY=`/bin/date -d '-1 day' +%d`

# Make sure that the year folder exists
if [ ! -d $BACKUP_DIR/$YEAR ]; then
    $MKDIR $BACKUP_DIR/$YEAR
fi

# Make sure that the month folder exists
if [ ! -d $BACKUP_DIR/$YEAR/$MONTH ]; then
    $MKDIR $BACKUP_DIR/$YEAR/$MONTH
fi

# Make sure that the day folder exists
if [ ! -d $BACKUP_DIR/$YEAR/$MONTH/$DAY ]; then
    $MKDIR $BACKUP_DIR/$YEAR/$MONTH/$DAY
fi

# Make the exclude list
EXCLUDE_STRING=""
for ((i=0;i<${#EXCLUDE[*]};i++)); do
    EXCLUDE_STRING="${EXCLUDE_STRING} --exclude '${EXCLUDE[${i}]}'"
done

# If it is the first day of the month, create a full backup.
if [ $DAY -eq 1 ]; then
    # Loop though each directory to backup
    for ((i=0;i<${#SOURCE_LOC[*]};i++)); do
        # Make sure the backup directory is created
        if [ ! -d $BACKUP_DIR/$YEAR/$MONTH/$DAY/${SOURCE_DIR[${i}]} ]; then
            $MKDIR $BACKUP_DIR/$YEAR/$MONTH/$DAY/${SOURCE_DIR[${i}]}
        fi

        # RSYNC     
        $RSYNC -a $EXCLUDE_STRING ${SOURCE_LOC[${i}]}/ $BACKUP_DIR/$YEAR/$MONTH/$DAY/${SOURCE_DIR[${i}]}/
        
        # Log that we've done the backup
        $LOGGER -p daemon.info [BACKUP] Performed full backup of ${SOURCE_DIR[${i}]}.
    done
else
    # INCREMENTAL
    
    # Loop though each directory to backup
    for ((i=0;i<${#SOURCE_LOC[*]};i++)); do
        # Create a copy with hard links
        $CP -al $BACKUP_DIR/$YEAR/$MONTH/$YESTERDAY/${SOURCE_DIR[${i}]} $BACKUP_DIR/$YEAR/$MONTH/$DAY/${SOURCE_DIR[${i}]}
        
        # RSYNC
        $RSYNC -aHx --numeric-ids --delete $EXCLUDE_STRING --delete-excluded \
            ${SOURCE_LOC[${i}]}/ $BACKUP_DIR/$YEAR/$MONTH/$DAY/${SOURCE_DIR[${i}]}/
        
        # Log that we've done the backup
        $LOGGER -p daemon.info [BACKUP] Performed incremental backup of ${SOURCE_DIR[${i}]}.
    done
fi