Rsync time backup

This script offers Time Machine-style backup using rsync. It creates incremental backups of files and directories to the destination of your choice. The backups are structured in a way that makes it easy to recover any file at any point in time.

It works on Linux, macOS and Windows (via WSL or Cygwin). The main advantage over Time Machine is the flexibility as it can backup from/to any filesystem and works on any platform. You can also backup, for example, to a Truecrypt drive without any problem.

On macOS, it has a few disadvantages compared to Time Machine - in particular it does not auto-start when the backup drive is plugged (though it can be achieved using a launch agent), it requires some knowledge of the command line, and no specific GUI is provided to restore files. Instead files can be restored by using any file explorer, including Finder, or the command line.

Installation

git clone https://github.com/laurent22/rsync-time-backup

Usage

Usage: rsync_tmbackup.sh [OPTION]... <[USER@HOST:]SOURCE> <[USER@HOST:]DESTINATION> [exclude-pattern-file]

Options
 -p, --port           SSH port.
 -h, --help           Display this help message.
 -n, --dry-run        Performs a dry run, i.e. output without the backup (log files will be generated)
 -L, --follow <path>  Follow a specified symlink instead of copying it as a symlink. Declare this
                      for each path. Paths cannot contain any single quote characters.
                      If using this option, the SOURCE and all followed symlink paths need to specify
                      where to start including what rsync calls 'implied paths', i.e., the parts of the
                      path that show up on the destination. To do this, place a dot-slash in the path
                      where you want it to start.
                      Example: /foo/bar/baz/abc.txt will copy to /dest/foo/bar/baz/abc.txt, but
                             /foo/bar/./baz/abc.txt will copy to /dest/baz/abc.txt
 --rsync-get-flags    Display the default rsync flags that are used for backup.
 --rsync-set-flags    Set the rsync flags that are going to be used for backup.
 --log-dir            Set the log file directory. If this flag is set, generated files will
                      not be managed by the script - in particular they will not be
                      automatically deleted.
 --strategy           Set the expiration strategy. Default: "1:1 30:7 365:30" means after one
                      day, keep one backup per day. After 30 days, keep one backup every 7 days.
                      After 365 days keep one backup every 30 days.
 --no-auto-expire     Set option to disable automatically purging old backups when out of space.

Features

Each backup is on its own folder named after the current timestamp. Files can be copied and restored directly, without any intermediate tool.
Backup to/from remote destinations over SSH.
Files that haven't changed from one backup to the next are hard-linked to the previous backup so take very little extra space.
Safety check - the backup will only happen if the destination has explicitly been marked as a backup destination.
Resume feature - if a backup has failed or was interrupted, the tool will resume from there on the next backup.
Exclude file - support for pattern-based exclusion via the --exclude-from rsync parameter.
Automatically purge old backups - within 24 hours, all backups are kept. Within one month, the most recent backup for each day is kept. For all previous backups, the most recent of each month is kept.
"latest" symlink that points to the latest successful backup.
Configuration testing of the command may be performed using the --dry-run parameter.
Specify only the symlinks you want to follow with the --follow <path> or -L <path> parameter. See example below.

Examples

Backup the home folder to backup_drive

  rsync_tmbackup.sh /home /mnt/backup_drive

Backup with exclusion list:

  rsync_tmbackup.sh /home /mnt/backup_drive excluded_patterns.txt

Backup to remote drive over SSH, on port 2222:

  rsync_tmbackup.sh -p 2222 /home user@example.com:/mnt/backup_drive

Backup from remote drive over SSH:

  rsync_tmbackup.sh user@example.com:/home /mnt/backup_drive

To mimic Time Machine's behaviour, a cron script can be setup to backup at regular interval. For example, the following cron job checks if the drive "/mnt/backup" is currently connected and, if it is, starts the backup. It does this check every 1 hour.
```
  0 */1 * * * if [[ -d /mnt/backup ]]; then rsync_tmbackup.sh /home /mnt/backup; fi
```
Follow a symlink that normally is copied as a symlink. (This works well on a CYGWIN system where the local drives aren't technically symlinks, but mounted drives.) In this example, the /home folder is still backed up to /mnt/backup_drive. Say there's a symlink at /home/some/folder that you want to follow. Add it as to the parameters list with -L or --follow:

rsync_tmbackup.sh -L /home/./some/folder/ /home/./ /mnt/backup_drive

Note: this only works because of rsync's (>=3.0.0) --relative parameter. A dot-slash must be placed before the path component in the SOURCE and follow paths that will be replicated on the destination (shuold be the same position). Read more dettail here.

On a CYGWIN system, if multiple local drives are to be included in the backup, rsync will not automatically follow the folder mountpoints in /cygdrive to specificed drives. This method must be used in this case. For example, to backup both the C: and D: drives within cygwin (extra spaces for clarity):

rsync_tmbackup.sh -L /cygdrive/./c/ -L /cygdrive/./d/ /home/./ /mnt/backup_drive

Without the ./, the files would be copied to /mnt/backup_drive/cygwin/c instead of /mnt/backup_drive/c. Lastly, the trailing slash after the dot is required if no folder comes after it (correct: /home/./, incorrect: /home/.). The trailing slash after a --follow symlink is usually required (this script will added it if missing), unless you have an exclusions text file that specifically mentions that folder with a trailing slash.

Backup expiration logic

Backup sets are automatically deleted following a simple expiration strategy defined with the --strategy flag. This strategy is a series of time intervals with each item being defined as x:y, which means "after x days, keep one backup every y days". The default strategy is 1:1 30:7 365:30, which means:

After 1 day, keep one backup every 1 day (1:1).
After 30 days, keep one backup every 7 days (30:7).
After 365 days, keep one backup every 30 days (365:30).

Before the first interval (i.e. by default within the first 24h) it is implied that all backup sets are kept. Additionally, if the backup destination directory is full, the oldest backups are deleted until enough space is available.

Exclusion file

An optional exclude file can be provided as a third parameter. It should be compatible with the --exclude-from parameter of rsync. See this tutorial for more information.

Built-in lock

The script is designed so that only one backup operation can be active for a given directory. If a new backup operation is started while another is still active (i.e. it has not finished yet), the new one will be automaticalled interrupted. Thanks to this the use of flock to run the script is not necessary.

Rsync options

To display the rsync options that are used for backup, run ./rsync_tmbackup.sh --rsync-get-flags. It is also possible to add or remove options using the --rsync-set-flags option. For example, to exclude backing up permissions and groups:

rsync_tmbackup --rsync-set-flags "--numeric-ids --links --hard-links \
--one-file-system --archive --no-perms --no-groups --itemize-changes" /src /dest

No automatic backup expiration

An option to diable the default behaviour to purge old backups when out of space. This option is set with the --no-auto-expire flag.

How to restore

The script creates a backup in a regular directory so you can simply copy the files back to the original directory. You could do that with something like rsync -aP /path/to/last/backup/ /path/to/restore/to/. Consider using the --dry-run option to check what exactly is going to be copied. Use --delete if you also want to delete files that exist in the destination but not in the backup (obviously extra care must be taken when using this option).

Extensions

rtb-wrapper: Allows creating backup profiles in config files. Handles both backup and restore operations.
time-travel: Smooth integration into OSX Notification Center

TODO

Check source and destination file-system (df -T /dest). If one of them is FAT, use the --modify-window rsync parameter (see man rsync) with a value of 1 or 2
Add --whole-file arguments on Windows? See http://superuser.com/a/905415/73619
Minor changes (see TODO comments in the source).

LICENSE

The MIT License (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

tralston/rsync-time-backup