不带-it参数运行容器时SimpleHTTPServer一行输出缺失原因问询

Hey there! Let's break down exactly why your Experiment 2 gave you that outcome, using your setup details (Docker 17.12.0-ce, macOS Terminal 2.8, High Sierra 10.13.1) as context.

First, let's clarify what the -it flag combo from Experiment 1 does—this is the core difference between your two tests:

• -i (interactive): Maintains an open standard input (STDIN) stream for the container, even when no terminal is actively attached. This lets you send commands or signals (like Ctrl+C) to the container later.
• -t (tty): Allocates a pseudo-terminal (pseudo-TTY) inside the container. This emulates a real terminal environment, ensuring the container's output (like SimpleHTTPServer's request logs) is formatted correctly with real-time updates, line breaks, and terminal-specific code handling.

Assuming Experiment 2 ran without the -it flags (the most common comparison scenario), here's what's driving the different results:

1. Log output is buffered (or invisible in real time) #

SimpleHTTPServer runs as a foreground process that logs every incoming request to STDOUT. Without the -t flag, Docker doesn't treat the container's output as a terminal session. This means the server's logs get buffered instead of printed to your terminal immediately. You might only see all logs at once when the container stops, or not see anything at all unless you explicitly retrieve them with docker logs <container-id>.

2. Direct container interaction is blocked #

Without -i, the container's STDIN stream is closed. If you tried to press Ctrl+C to stop the server from your original terminal, nothing would happen—you'd have to switch to another terminal and run docker stop <container-id> instead. Even if you later use docker attach to connect to the running container, you won't be able to send input to it because STDIN wasn't kept open.

3. Detached mode (-d) without -it keeps the server running but hidden #

If Experiment 2 used detached mode (-d) without -it, the SimpleHTTPServer would still run normally (which is why your cross-terminal test worked). The only difference is you won't see any logs in your local terminal—you have to fetch them with docker logs because the container's output isn't tied to your host terminal session.

A quick macOS-specific note: Docker on High Sierra runs inside a hidden Linux VM (since Docker relies on Linux kernel features). This doesn't alter the -it behavior, but it explains why your host terminal interacts with the container through that VM—all TTY settings are passed through correctly, so the core logic matches native Linux hosts.

内容的提问来源于stack exchange，提问作者Lone Learner