Environment Variable

Definition of Environment Variable

An environment variable is a dynamic-named value, stored within a computer’s operating system, that can influence the behavior of running processes and applications. It acts as a means to store configuration data, such as file paths, and allows for easy modification by system administrators without altering the source code. These variables can be accessed and manipulated by applications, scripts, and users to customize the way a system operates.


The phonetic transcription for the keyword “Environment Variable” is:/ɛnˈvaɪrənmənt ˈvɛriəbəl/

Key Takeaways

  1. Environment variables are key-value pairs that are used to store configuration information and settings for applications, processes, or user profiles.
  2. They help in simplifying the development and deployment of applications by allowing developers to separate configuration details from the application code.
  3. Environment variables can be accessed and modified programmatically, making it easy to update application configurations without the need to modify and rebuild the application.

Importance of Environment Variable

Environment variables are essential in the technology realm as they enable efficient management and configuration of software systems.

They store critical information such as paths, settings, and resources needed for certain applications to function correctly across multiple execution environments.

By acting as a globally accessible container for information, environment variables allow seamless interaction between various programs, developers, and systems.

Furthermore, they facilitate flexibility and portability between different operating systems, ensuring adaptability when transferring software solutions.

Overall, environment variables are fundamental in streamlining workflows and enhancing maintainability by centralizing key configuration data, making them an indispensable aspect of software development and operation.


Environment variables serve as a crucial element in software development and system administration, as they allow for a more dynamic and flexible configuration of applications and systems. Their purpose lies in the ability to store values that dictate how an application or process behaves, acting as changeable parameters that enable systems to adapt to different operating conditions without any direct alterations to the code or how the program runs.

By using environment variables, developers can distinguish between various environments, such as test, staging, and production, by adjusting the values to meet the specific requirements for each scenario. This ability ultimately facilitates a less error-prone and more streamlined development process, as the same code can be executed in multiple environments without manual intervention.

Environment variables are widely utilized in different aspects of software development and computing operations, including system paths, configurations, and data sharing. They can store data like file and folder locations, API keys, credentials, or software version information so that the applications can read and write data to appropriate places accordingly.

Also, environment variables can be inherited, meaning that values set at a higher level can be passed down through running processes within a system, further enhancing adaptability. In essence, the versatility of environment variables promotes the creation of manageable and scalable applications with heightened efficiency and consistency across various systems and platforms.

Examples of Environment Variable

Web Application Deployment: When deploying web applications, developers often use environment variables to store sensitive information such as API keys, database credentials, and other configurations. For instance, in a Node.js application using the Express framework, a developer can use environment variables to store the database connection string and port number. By doing so, these confidential details remain hidden and do not end up hardcoded in the application code.

Container Management: In container management systems like Docker or Kubernetes, environment variables play a crucial role in sharing configuration data among containers. For example, a developer can set environment variables in a Dockerfile to configure an application running inside a Docker container. They can also pass those variables at runtime, allowing for easy updates or changes to the container’s environment. These systems make it simple to apply custom configurations across different staging environments such as development, testing, and production.

Build and Deployment Pipelines: In continuous integration and deployment (CI/CD) pipelines, environment variables are used to manage various settings and unique identifiers. For example, a developer may utilize environment variables in a Jenkins pipeline to store information about the build version, server address, and credentials required to access repositories and deploy applications. By doing so, sensitive data is kept secure, and developers can avoid hardcoding server details or credentials directly in their pipeline scripts.

Environment Variable FAQ

1. What is an environment variable?

An environment variable is a dynamic object containing configuration data or settings that a system, application, or process can use during its execution. They provide a convenient and flexible way to manage configurations without hardcoding values into the application code.

2. How do I set an environment variable?

In most operating systems, you can set an environment variable through command line or system settings. For example, in Windows, you can use the ‘setx’ command, while in Linux or macOS, you can use the ‘export’ command. Be sure to consult your operating system’s documentation for specific instructions.

3. How do I access an environment variable in my program or script?

Accessing environment variables will depend on the programming language you are using. Common languages like Python, Node.js, and Java have methods to read environment variables. For instance, in Python, you can use ‘os.environ’, while in Node.js, you can use ‘process.env’.

4. Are environment variables secure?

Environment variables can be a secure way to store sensitive information, such as API keys and secrets, if properly managed. However, be aware that environment variables can be accessed by any process running under the same user context, so care should be taken to minimize the risk of exposing sensitive data.

5. What is the difference between system and user environment variables?

System environment variables are global and available to all users and processes on a system. User environment variables, on the other hand, are specific to an individual user account and only accessible to processes running as that user. Utilizing user environment variables can provide a level of security by isolating sensitive data to specific user accounts.

Related Technology Terms

  • Path
  • System Properties
  • Configuration Files
  • Shell Variables
  • Operating System

Sources for More Information


About The Authors

The DevX Technology Glossary is reviewed by technology experts and writers from our community. Terms and definitions continue to go under updates to stay relevant and up-to-date. These experts help us maintain the almost 10,000+ technology terms on DevX. Our reviewers have a strong technical background in software development, engineering, and startup businesses. They are experts with real-world experience working in the tech industry and academia.

See our full expert review panel.

These experts include:


About Our Editorial Process

At DevX, we’re dedicated to tech entrepreneurship. Our team closely follows industry shifts, new products, AI breakthroughs, technology trends, and funding announcements. Articles undergo thorough editing to ensure accuracy and clarity, reflecting DevX’s style and supporting entrepreneurs in the tech sphere.

See our full editorial policy.

More Technology Terms

Technology Glossary

Table of Contents