In the foreground mode, the console you are using to execute docker run will be attached to standard input, output, and error streams. This is the default; Docker will attach STDIN, STDOUT and STDERR streams to your shell console. If you need to, you can change this behavior and use the -a switch for the docker run command. As a parameter for the -a switch, you use the name of the stream you want to attach to the console. For example:
$ docker run -a stdin -a stdout -i -t centos /bin/bash
The preceding command will attach both stdin and stdout streams to your console.
The useful docker run options are the -i or --interactive (for keeping STDIN stream open, even if not attached) and -t or -tty (for attaching a pseudo-tty) switches, ...