envar

Envar, short for environment variable, is a dynamic named value that can affect the way running processes will behave on a computer. Environment variables are part of the operating system's environment. They are a set of external parameters that are passed to a program.

Typically, environment variables are used to store system-wide settings or configuration information that applications might need. For example, a program might look for an environment variable named "PATH" to determine where to find executable files. Another common use is storing sensitive information like API keys or database credentials, which can be accessed by applications without hardcoding them directly into the source code. This practice enhances security and makes it easier to manage configurations across different environments (like development, staging, and production).

Each operating system has its own way of managing environment variables. On Linux and macOS, they can be set from the command line using commands like export, or they can be configured in shell startup files (like .bashrc or .zshrc). On Windows, environment variables can be managed through the System Properties dialog box.

Applications can access and modify environment variables. This allows for flexible configuration and customization without altering the program's code. The specific names and purposes of environment variables are often defined by the operating system or by the software that uses them. Understanding and utilizing environment variables is a fundamental skill for system administrators and software developers.