Editing Environment variable (section)

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{{short description|User-definable variable associated with each running process in many operating systems}}
{{Use dmy dates|date=April 2019|cs1-dates=y}}
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An '''environment variable''' is a user-definable [[Value (computer science)|value]] that can affect the way running [[process (computing)|processes]] will behave on a computer. Environment variables are part of the environment in which a process runs. For example, a running process can query the value of the TEMP environment variable to discover a suitable location to store [[temporary file]]s, or the HOME or USERPROFILE variable to find the [[directory structure]] owned by the user running the process.

They were introduced in their modern form in 1979 with [[Version 7 Unix]], so are included in all [[Unix]] [[operating system]] flavors and variants from that point onward including [[Linux]] and [[macOS]]. From [[PC&nbsp;DOS 2.0]] in 1982, all succeeding [[Microsoft]] operating systems, including [[Microsoft Windows]], and [[OS/2]] also have included them as a feature, although with somewhat different syntax, usage and standard variable names.