# Variables de Entorno { #environment-variables }

/// tip | Consejo

Si ya sabes qué son las "variables de entorno" y cómo usarlas, siéntete libre de saltarte esto.

///

Una variable de entorno (también conocida como "**env var**") es una variable que vive **fuera** del código de Python, en el **sistema operativo**, y podría ser leída por tu código de Python (o por otros programas también).

# Environment Variables { #environment-variables }

/// tip

If you already know what "environment variables" are and how to use them, feel free to skip this.

///

An environment variable (also known as "**env var**") is a variable that lives **outside** of the Python code, in the **operating system**, and could be read by your Python code (or by other programs as well).

<div class="termy">

```console
// Aqui ainda não definimos a variável de ambiente
$ python main.py

// Como não definimos a variável de ambiente, obtemos o valor padrão

Hello World from Python

// Mas se criarmos uma variável de ambiente primeiro
$ export MY_NAME="Wade Wilson"

// E então chamar o programa novamente
$ python main.py

// Agora ele pode ler a variável de ambiente

Hello Wade Wilson from Python
```

## `PATH`-Umgebungsvariable { #path-environment-variable }

Es gibt eine **spezielle** Umgebungsvariable namens **`PATH`**, die von den Betriebssystemen (Linux, macOS, Windows) verwendet wird, um Programme zu finden, die ausgeführt werden sollen.

$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python
```

</div>

////

//// tab | Windows PowerShell

<div class="termy">

$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python
```

</div>

////

//// tab | Windows PowerShell

<div class="termy">

在許多情況下，環境變數的用途和適用性可能不會立刻顯現。但是在開發過程中，它們會在許多不同的場景中出現，因此瞭解它們是非常必要的。

:end
@rem End local scope for the variables with windows NT shell
if %ERRORLEVEL% equ 0 goto mainEnd

:fail
rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
rem the _cmd.exe /c_ return code!
set EXIT_CODE=%ERRORLEVEL%
if %EXIT_CODE% equ 0 set EXIT_CODE=1
if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
exit /b %EXIT_CODE%

:mainEnd
if "%OS%"=="Windows_NT" endlocal

   * add the suppression to the whole method (which turns off checking for a large section of code),
   * or extract a variable, and put the suppression on that. However, a local variable typically
   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the

   * add the suppression to the whole method (which turns off checking for a large section of code),
   * or extract a variable, and put the suppression on that. However, a local variable typically
   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the