Novel (?) incremental backup using rsync without hardlinks.

rsync-incremental-backup.sh

#!/bin/sh
#
# Novel (?) rsync incremental backup without hardlinks
# Pol Llovet <pol.llovet@montana.edu>

case "$2" in
  '')
  ;&
  '-h')
  ;&
  '--help')
    echo $"Usage: $0 {SRC_PATH} {DEST_PATH}"
    echo $"       Full paths required."
    exit 1
  ;;
  *)
    backup_dir=$2
    source_dir=$1
  ;;
esac

# Names
backup_name=`date +%Y-%m-%d-%H%M%S`
backup_increment_dir="$backup_dir/${backup_name//-//}"

# Supporting Dirs
manifest_dir="$backup_dir/manifest"

# Logs & Manifest
log="$backup_dir/current.log"
backup_manifest="$manifest_dir/$backup_name.manifest"
backup_log="$backup_dir/$backup_name.log"

# Rsync options
check_current="--dry-run -Wiah . $backup_dir/current"
create_increment="-Wah --stats --compare-dest=$backup_dir/current . $backup_increment_dir"
update_current="-Wah --delete --stats . $backup_dir/current"

# make sure target dirs exist
if [ ! -d $backup_dir/current ]; then mkdir -p $backup_dir/current; fi
if [ ! -d $manifest_dir ]; then mkdir -p $manifest_dir; fi

echo "========== $backup_name ==========" >> $log

cd $source_dir

rsync $check_current > $backup_manifest

if [ -s $backup_manifest ]; then
    2>&1 rsync $create_increment > $backup_log
    if [ $? != 0 ]; then echo "Errors in increment creation! See $backup_log."; fi
    2>&1 rsync $update_current >> $log
    if [ $? != 0 ]; then echo "Errors in current backup update! See $log."; fi
    tar --remove-files -czf $backup_dir/$backup_name.tgz $backup_log $backup_increment_dir
else
    # no changes, nothing to do, rm the empty manifest
    rm -f $backup_manifest
    echo "No changes to $source_dir. Nothing to back up."
fi

exit 0

Because of this http://stackoverflow.com/questions/13993236/why-rsync-uses-mkdir-without-p-option

i suggest to add after
if [ ! -d $backup_dir/current ]; then mkdir -p $backup_dir/current; fi
if [ ! -d $manifest_dir ]; then mkdir -p $manifest_dir; fi

This line to avoid rsync errors complaining about "rsync: mkdir failed: No such file or directory (2)"
if [ ! -s $backup_increment_dir ]; then mkdir -p $backup_increment_dir; fi