This article aims to explore the difference between the functions os.getenv and os.environ.get in Python. These functions are used to retrieve the value of environment variables, but they differ in terms of functionality, performance, version-specific details, and behavior in relation to os.putenv.

While both functions serve the same purpose, os.getenv is a wrapper for os.environ.get and returns a default value if the variable is not found in os.environ. On the other hand, os.environ.get does not throw a KeyError and returns None instead.

In terms of performance, the difference between the two functions is minimal, with os.getenv being a microsecond timeit in Python.

Furthermore, version-specific details reveal that os.getenv is a simple wrapper for os.environ.get in various Python versions.

It is important to note that os.putenv differs significantly from os.getenv and os.environ.get as it modifies the actual OS-level environment variables, unlike the latter two functions.

Overall, this article will provide an objective analysis of the differences between os.getenv and os.environ.get, offering insights into their functionality, performance, and version-specific details.

Functionality and Usage

Os.getenv and os.environ.get have the same functionality, with os.getenv serving as a shortcut to os.environ.get in CPython and being used when a default value is desired if an environment variable is not found in os.environ. Both methods return None if the environmental variable does not exist.

However, there are some differences between the two. While os.environ.get does not throw a KeyError, accessing os.environ[] directly raises an exception if the environmental variable does not exist.

Additionally, os.putenv is not recommended as it changes the actual OS-level environment variables but does not reflect those changes when using os.getenv or other standard library ways of inspecting environment variables.

Overall, os.getenv is a simple wrapper around os.environ.get, providing a convenient way to handle environment variables.

Performance and Overhead

In terms of performance and overhead, the usage of os.getenv and os.environ.get exhibits minimal differences and both options provide efficient functionality.

The performance disparity between the two is negligible, with os.getenv being a microsecond timeit in Python.

While os.getenv is a wrapper for os.environ.get, it introduces only minimal overhead in Python versions 3.7.1 and 3.7.2.

Directly accessing os.environ may have slightly less overhead, but the difference is insignificant.

Additionally, os.putenv, which changes the actual OS-level environment variables, requires a ctypes call to reflect the changes made.

Therefore, os.getenv and os.environ.get are preferred in terms of performance and convenience as they offer similar functionality and incur minimal overhead.

Version Specific Details

Python versions 2.7 and 3.8 have the same functionality for os.environ.get and os.getenv. Both methods retrieve the value of an environmental variable. They return None if the variable does not exist.

However, there are some version-specific details for os.getenv.

In Python 2.7 and Python 3, os.getenv is a simple wrapper around os.environ.get. This means that os.getenv can be used interchangeably with os.environ.get in these versions.

In Python 3.7.2, os.getenv is specifically implemented as a wrapper for os.environ.get. Similarly, in Python 3.7.1 on macOS Mojave, os.getenv is also a wrapper for os.environ.get.

Overall, the functionality of os.environ.get and os.getenv remains consistent across these Python versions, with os.getenv serving as a convenient wrapper for os.environ.get.