Why the 'i' option of the docker start command does possible display a command's output?

[rimelek (Ákos Takács)]

Since it is related to your other question and I wrote about TTY and standard input as well, and linked anothe rpost which was about attaching to the standard streams, I just link the other topic here too

Trying to understand the relation of tty between the host and container when the docker run command is executed

My old reply in another topic could be useful here: In your case, the TTY is not for having an output. Some programs like a shell need a pseudo TTY to be able to run. You run the following command: docker run -d --name bash-1 bash It will run and stop immediately. Now run this: docker run -d --name bash-2 -t bash It will keep running. Or just try to run it in interactive mode: docker run --rm -i bash You can type characters, but there is nothing to handle what you typed without the TTY. …

But again the interactivity has nothing to do with the output. Commands will run, you will just not be able to work interactively.

@manueljordan

Why happens this if the i option is based on the STDIN stream?

You didn’t do anything with the standard input, did you?