Obnam, a backup program

Obnam is a backup program.

Home page

The Obnam home page is at http://liw.fi/obnam/, see there for more information.


The source tree contains packaging for Debian. Run debuild -us -uc -i.git to build an installation package.

On other systems, using the setup.py file should work: run "python setup.py --help" for advice. If not, please report a bug. (I've only tested setup.py enough for to build the Debian package.)

You need Python 2.6 or 2.7 (Python 3 is not yet supported). You also need to install my Python B-tree library, and some of my other libraries and tools, which you can get from:

You also need third party libraries:

See debian/control for the full set of build dependencies and runtime dependencies on a Debian system. (That set actually gets tested. The above list is maintained manually and may get out of date from time to time.)


To get a quick help summary of options:

./obnam --help

To make a backup:

./obnam backup --repository /tmp/mybackup $HOME

For more information, see the manual page:

man -l obnam.1


Obnam source code is stored in git for version control purposes; you can get a copy as follows:

git clone git://git.liw.fi/obnam

The 'master' branch is the main development one. Any bug fixes and features should be developed in a dedicated branch, which gets merged to master when the changes are done and considered good.

To build and run automatic tests:

./check --fast # unit tests only, no black box tests
./check --network # requires ssh access to localhost

check is a wrapper around python setup.py, but since using that takes several steps, the script makes things easier.

You need my CoverageTestRunner to run tests, see above for where to get it. A couple of scripts exist to run benchmarks and profiles:

./metadata-speed 10000
./obnam-benchmark --size=1m/100k --results /tmp/benchmark-results
viewprof /tmp/benchmark-results/*/*backup-0.prof
seivots-summary /tmp/benchmark-results/*/*.seivot | less -S

There are two kinds of results: Python profiling output, and .seivot files.

For the former, viewprof is a little helper script I wrote, around the Python pstats module. You can use your own, or get mine from extrautils (http://liw.fi/extrautils/). Running the benchmarks under profiling makes them a little slower (typically around 10% for me, when I've compared), but that's OK: the absolute numbers of the benchmarks are less important than the relative ones. It's nice to be able to look at the profiler output, if a benchmark is surprisingly slow, without having to re-run it.

seivots-summary is a tool to display summaries of the measurements made during a benchmark run. seivot is the tool that makes the measurements. I typically save a number of benchmark results, so that I can see how my changes affect performance over time.

If you make any changes, I welcome patches, either as plain diffs, git format-patch --cover-letter mails, or public repositories I can merge from.

The code layout is roughly like this:

obnamlib/               # all the real code
obnamlib/plugins/       # the plugin code (see pluginmgr.py)
obnam                   # script to invoke obnam
_obnammodule.c          # wrapper around some system calls

In obnamlib, every code module has a corresponding test module, and "make check" uses CoverageTestRunner to run them pairwise. For each pair, test coverage must be 100% or the test will fail. Mark statements that should not be included in coverage test with "# pragma: no cover", if you really, really can't write a test. without-tests lists modules that have no test modules.

If you want to make a new release of Obnam, I recommend following my release checklist: http://liw.fi/obnam/release/.


I welcome bug fixes, enhancements, bug reports, suggestions, requests, and other feedback. I prefer e-mail the mailing list: see http://vlists.pepperfish.net/cgi-bin/mailman/listinfo/obnam-flarn.net for instructions.

It would be helpful if you can run make clean check before submitting a patch, but it is not strictly required.

Legal stuff

Most of the code is written by Lars Wirzenius. (Please provide patches so that can change.)

This entire work is covered by the GNU General Public License, version 3 or later.

Copyright 2010-2013 Lars Wirzenius

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

A copy of the GPL is included in the file COPYING in the source tree.

The manual (all the contents of the manual subdirectory) is additionally licensed under a Creative Commons Attribution 4.0 International License. You can choose whether to use the GPL or the CC license for the manual.

A copy of the Creative Commons license is included in the file CC-BY-SA-4.0.txt in the source tree, and can be viewed online at http://creativecommons.org/licenses/by-sa/4.0/legalcode.