You can also create an environment variable only for a **specific program invocation**, that is only available to that program, and only for its duration.

To do that, create it right before the program itself, on the same line:

<div class="termy">

```console
// Create an env var MY_NAME in line for this program call
$ MY_NAME="Wade Wilson" python main.py

// Now it can read the environment variable

## Server Machine and Server Program { #server-machine-and-server-program }

There's a small detail about names to keep in mind. 💡

The word "**server**" is commonly used to refer to both the remote/cloud computer (the physical or virtual machine) and also the program that is running on that machine (e.g. Uvicorn).

---

Then the next concepts to consider are all about the program running your actual API (e.g. Uvicorn).

## Program and Process { #program-and-process }

We will talk a lot about the running "**process**", so it's useful to have clarity about what it means, and what's the difference with the word "**program**".

### What is a Program { #what-is-a-program }

The word **program** is commonly used to describe many things:

A GODEBUG setting is a `key=value` pair
that controls the execution of certain parts of a Go program.
The environment variable `GODEBUG`
can hold a comma-separated list of these settings.
For example, if a Go program is running in an environment that contains

	GODEBUG=http2client=0,http2server=0

then that Go program will disable the use of HTTP/2 by default in both
the HTTP client and the HTTP server.

         'https://repo.msys2.org/distrib/x86_64/msys2-base-x86_64-20240727.tar.xz', \
         'msys2.tar.xz'); \
    Start-Process -FilePath \"C:\Program Files\7-Zip\7z.exe\" -ArgumentList 'x msys2.tar.xz -oC:\TEMP\msys2.tar' -Wait; \
    Start-Process -FilePath \"C:\Program Files\7-Zip\7z.exe\" -ArgumentList 'x C:\TEMP\msys2.tar -oC:\tools' -Wait; \

And then, there would be another program (in some cases it's another program, in some cases it could be the same TLS Termination Proxy) that would talk to Let's Encrypt, and renew the certificate(s).

<img src="/img/deployment/https/https.drawio.svg">

The **TLS certificates** are **associated with a domain name**, not with an IP address.

* `/usr/bin`
* `/bin`
* `/usr/sbin`
* `/sbin`

////

//// tab | Windows

```plaintext
C:\Program Files\Python312\Scripts;C:\Program Files\Python312;C:\Windows\System32
```

이는 시스템이 다음 디렉토리에서 프로그램을 찾아야 함을 의미합니다:

* `C:\Program Files\Python312\Scripts`
* `C:\Program Files\Python312`
* `C:\Windows\System32`

////

터미널에 **명령어**를 입력하면 운영 체제는 `PATH` 환경 변수에 나열된 **각 디렉토리**에서 프로그램을 **찾습니다.**

-   `/usr/bin`
-   `/bin`
-   `/usr/sbin`
-   `/sbin`

////

//// tab | Windows

```plaintext
C:\Program Files\Python312\Scripts;C:\Program Files\Python312;C:\Windows\System32
```

這意味著系統應該在以下目錄中查找程式：

-   `C:\Program Files\Python312\Scripts`
-   `C:\Program Files\Python312`
-   `C:\Windows\System32`

////

當你在終端機中輸入一個**指令**時，作業系統會在 `PATH` 環境變數中列出的**每個目錄**中**查找**程式。

A `requirements.txt` with some packages could look like:

```requirements.txt
fastapi[standard]==0.113.0
pydantic==2.8.0
```

///

## Run Your Program { #run-your-program }

After you activated the virtual environment, you can run your program, and it will use the Python inside of your virtual environment with the packages you installed there.

<div class="termy">

```console
$ python main.py

* [NGINX Unit](https://unit.nginx.org/howto/fastapi/): NGINX Unit — лёгкая и многофункциональная среда выполнения веб‑приложений.

## Сервер как машина и сервер как программа { #server-machine-and-server-program }

Есть небольшой нюанс в терминологии, о котором стоит помнить. 💡