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cmp_version

A script and python module to compare version numbers. Use this to compare the version strings of packages, modules, really anything.

Since version 3.0, cmp_version supports all kinds of complex version numbers, including those with releases ( like $version-5 ) or Epochs (like 5:$version)

Commandline Tool

You can use the provided cmp-version tool to compare two version strings.

It will print to stdout "-1" if version1 is less/older than version2, "0" if they are equal, and "1" if version1 is greater/newer than version2.

Examples:

$ ./cmp-version 1.0.1b 1.0.1a

1

$ ./cmp-version 1.0.1b 1.0.2

-1

$ ./cmp-version 1.0 1.0.0

0

Comparing Filenames

Without actually scanning the contents of a package, you can from a script compare the versions based on the filenames.

Example:

$ cmp-version glibc-6.2.1-3.x86_64.rpm glibc-6.2.3-1.x86_64.rpm

-1

Method Signature

The cmp_version module provides a single method, cmp_version which compares two versions "cmp" style (think strcmp or the "cmp" operator in python<3).

def cmp_version(version1, version2):

'''

cmp_version - Compare two version strings, checking which one represents a "newer" (greater) release.

Note that even if two version strings are not equal string-wise, they may still be equal version-wise (e.x. 1.0.0 is the same version as 1.0)

@param version1 <str> - A version string

@param version2 <str> - A version string

@return <int>

-1 if version1 is older/less than version2

0 if version1 is equal to version2

1 if version1 is newer/greater than version2

So for example,

cmp_version('1.0.5b', '1.0.5a') would return 1 because 1.0.5b comes after 1.0.5a

Special Type

cmp_version provides a special type, "VersionString", which inherits string. All the comparison magic functions are implemented, such that you can directly compare VersionString objects.

Example:

>>> x = VersionString('0.1b2')
>>> y = VersionString('.2b2')
>>>
>>> '0.1b2' < '.2b2' # Show that as strings this version compare gives wrong answer

False

>>> x < y # Show that using VersionString objects, the comparison does work

True

Sorting Lists

You can sort a list of versions, or filenames containing versions etc like this:

>>> from cmp\_version import cmp\_version, VersionString
>>>
>>> x = ['.9a', '0.9', '0.9.0', '1.2c', '1.1b', '1.b4.0']
>>> sorted(x, key=VersionString)

['0.9', '0.9.0', '.9a', '1.1b', '1.2c', '1.b4.0']

Return value

  • 0 is returned when the two versions are equal, even if the strings are not equal (for example "1.0" is the same version as "1.0.0")
  • -1 is returned when version1 is older/less than version2
  • 1 is returned when version1 is newer/greater than version2.

License

This module is released under Public Domain.