python-dpkg/README.md

python-dpkg

This library can be used to:

1. read and extract control data from Debian-format package files, even on platforms that generally lack a native implementation of dpkg

2. compare dpkg version strings, using a pure Python implementation of the algorithm described at https://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version

This is primarily intended for use on platforms that do not normally ship python-apt due to licensing restrictions or the lack of a native libapt.so (e.g. macOS)

Currently only tested on Python 2.6 and 2.7. Should run on any python2 distribution that can install the arpy library.

Usage

Read and extract headers

>>> from pydpkg import Dpkg
>>> dp = Dpkg('/tmp/testdeb_1:0.0.0-test_all.deb')

>>> dp.headers
{'maintainer': u'Climate Corp Engineering <no-reply@climate.com>', 'description': u'testdeb\n a bogus debian package for testing dpkg builds', 'package': u'testdeb', 'section': u'base', 'priority': u'extra', 'installed-size': u'0', 'version': u'1:0.0.0-test', 'architecture': u'all'}

>>> print dp
Package: testdeb
Version: 1:0.0.0-test
Section: base
Priority: extra
Architecture: all
Installed-Size: 0
Maintainer: Climate Corp Engineering <no-reply@climate.com>
Description: testdeb
 a bogus debian package for testing dpkg builds

Get an arbitrary control header, case-independent

>>> dp.get_header('version')
u'1:0.0.0-test'

>>> dp.get_header('VERSION')
u'1:0.0.0-test'

Compare current version to a candidate version

>>> dp.compare_version_with('1.0')
1

>>> dp.compare_version_with('1:1.0')
-1

Compare two arbitrary version strings

>>> from pydpkg import Dpkg
>>> ver_1 = '0:1.0-test1'
>>> ver_2 = '0:1.0-test2'
>>> Dpkg.compare_versions(ver_1, ver_2)
-1

Use as a cmp function to sort a list of version strings

>>> from pydpkg import Dpkg
>>> sorted(['0:1.0-test1', '1:0.0-test0', '0:1.0-test2'] , cmp=Dpkg.compare_versions)
['0:1.0-test1', '0:1.0-test2', '1:0.0-test0']