Table of Contents

Python Environment Variables

Python environment variables are used to configure the Python interpreter and to influence the behavior of Python programs. Some common environment variables used in Python are as follows:

PYTHONPATH
PYTHONHOME
PYTHONSTARTUP
PYTHONCASEOK
PYTHONHASHSEED
PYTHONMALLOC

PYTHONPATH

This environment variable tells the Python interpreter where to locate the module files to import into the program. It plays a similar role to the PATH environment variable in Windows.

Python source library and code directories should be included in PYTHONPATH. If not set, Python will look in the default installation path for modules.

PYTHONHOME

This environment variable is used to set the default location for Python. If Python cannot find its home directory where the standard libraries are located, it will use this environment variable. If not set, Python uses the default paths. It is usually located in the PYTHONSTARTUP or PYTHONPATH directories to make switching module libraries easier.

PYTHONSTARTUP

This variable contains the path of an initialization file containing Python source code. It is executed every time you start the interpreter. It is named /pythonrc.py in Unix, comprising commands that load utilities or modify PYTHONPATH.

The /pythonrc.py file is a Python script that gets executed every time the Python interactive shell is started, but only if the PYTHONSTARTUP environment variable is set to its path. This mechanism is similar to the .bashrc or .bash_profile files used in Unix-like systems for Bash shell configurations.

PYTHONCASEOK

This environment variable is used on the Windows operating system to instruct Python to find the first case-insensitive match in an import statement. Set this variable to any value to activate it.

PYTHONHASHSEED

If this environment variable is set to “random,” the effect is the same as specifying the -R option: a random value is used to seed the hashes of str and bytes objects.

PYTHONMALLOC

Python will use the debug memory allocator if this variable is set to ‘debug’

These environment variables can be very helpful in managing the Python environment. They can also be used for debugging purposes or to change the behavior of Python interpreters and Python programs.

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