abus 3

Abingdon Backup Script

ABuS is a script for backing up (and restoring) your files to a local disk.

The backups are encrypted, compressed, and deduplicated. It is assumed that another program (e.g. rsync) is used to make off-site copies of the backups (see below).

ABuS only backs up file content at the moment. In particular the backups do not include permissions, symbolic links, hard links, or special files.

Missing Features

• Documentation

• Deletion of old backups

• “Flattening” of restores

• Restore target directory other than “.”

Installation

1. Install Python 3.6 from python.org

   • include pip

   • it helps to add python to path

2. From the command line, “as administrator” if python has been installed “for all users”:

   c:\path\to\python36\scripts\pip install abus

3. Create minimal config file, e.g.:

   logfile c:/my/home/abus.log
   archive e:/backups
   password password1234 just kidding!
   [include]
   c:/my/home

4. Initialise the backup directory and the cache database with

   c:\path\to\python36\scripts\abus.exe -f c:/my/home/abus.cfg --init

5. Add to Task Scheduler:

   c:\path\to\python36\scripts\abus.exe -f c:/my/home/abus.cfg --backup

   If there are any problems that prevent abus from getting as far as opening the log file (and Windows permissions can cause many such problems), then use cmd.exe to allow redirection:

   cmd /c c:\path\to\python36\scripts\abus.exe -f c:/my/home/abus.cfg --backup >c:\abus.err 2>&1

Documentation

Overview

ABuS is a single script for handling backups. Its command line parameters determine whether the backups are to be created, listed, or restored. The backups are stored in subdirectories of the backup directory which must be on a local filesystem. For off-site copies another program is to be used, for example rsync. N.B.: Off-site copies must be made correctly to minimise the risk of propagating any local corruption.

A configuration file is used to point to the backup directory, define the backup set, and some options. ABuS finds the configuration file either via a command line parameter or an environment variable.

Configuration file

The file has three sections

• parameters at the beginning

• inclusions

• exclusions

ABuS uses slashes as path separators internally. All filenames given in the config file or on the command line may use backslashes or slashes; all backslashes are converted to slashes.

Parameters

The first word of each line is a parameter name, the following words for the value. Leading and trailing spaces are trimmed while spaces within the value are preserved.

• logfile Specifies the path of a file to which all log entries are made. The parameter should be given first so that any subsequent errors in the configuration can be reported to the log.

• archive Specifies the path to the root backup directory containing all backup files and the cache database are written.

• password Specifies the encryption password to be used for all backup files. The encryption allows copying the backup archive to an offsite location.

Inclusions

A line containing the header [include] starts the inclusion section, each line of which is a directory path which will be backed up recursively. There must be at least one inclusion.

Exclusions

A line containing the header [exclude] starts the exclusion section, each line if which is a shell global pattern. All file paths that would be backed up (or directory paths that would be searched for files) are skipped if they match any of the patterns.

A * in the patterns also matches the directory separators. *.bak ignores any file with the extension .bak; */~* ignores any file or directory starting with a tilde.

Off-site copies

ABuS only backs up to local filesystems. This means that the backups themselves are subject to corruption, for example from ramsomware. It is important that another copy of the backup is made and that it fulfuls these criteria:

• It must not be on a local filesystem, so that the machine being backed up cannot corrupt it.

• Files must never be overwritten, once created, so that any local corruption does not propagate.

History

v3 (alpha) 2017-10-15

• feature: reconstruction of cache database from backup meta data

v2 (alpha) 2017-10-07

• not excruciatingly slow any more

v1 (alpha) 2017-10-04

• first version