In the requirements.txt for a Python library I am using, one of the requirements is specified like:
mock-django~=0.6.10
What does ~= mean?
It means it will select the latest version of the package, greater or equal to 0.6.10, but still in the 0.6.* version, so it won't download 0.7.0 for example. It ensures you will get security fixes but keep backward-compatibility, if the package maintainer respects the semantic versioning (which states that breaking changes should occur only in major versions).
Or, as said by PEP 440:
For a given release identifier V.N , the compatible release clause is approximately equivalent to the pair of comparison clauses:
>= V.N, == V.*
That's the 'compatible release' version specifier.
It's equivalent to: mock-django >= 0.6.10, == 0.6.*, and is a tidy way of matching a version which is expected to be compatible. In plain English, it's a bit like saying: "I need a version of mock-django which is at least as new as 0.6.10, but not so new that it isn't compatible with it."
If you're not sure about all this version number stuff, a quick look at the PEP440 version scheme should sort you out!
~= means a compatible version. Not less than 0.6.10 and higher (0.6.*).
A compatible release clause consists of the compatible release operator ~= and a version identifier. It matches any candidate version that is expected to be compatible with the specified version.
You can read more here: https://www.python.org/dev/peps/pep-0440/#compatible-release
来源：https://stackoverflow.com/questions/39590187/in-requirements-txt-what-does-tilde-equals-mean