Docker —Using docker run with interactive mode but without tty ( What happens? )

README.md

Docker — Using docker run with interactive mode but without tty ( What happens? )

Usually we into docker container with docker run command option like -it. But if not specified -t, what happens?

In the first place, what is tty?

$ docker run --help | grep tty
  -t, --tty                            Allocate a pseudo-TTY

Umm i don’t understand that enough, yet.

Pseudoterminal - Wikipedia

Trying

docker run --interactive alpine

No PRONPT mark

At first, you will find, console has no PRONPT mark. ( e.g # $ ) Console freezing? No you are already in the docker container's control.

Control arrow keys

You can not handle arrow keys well.

^[[C^[[C^[[C
/bin/sh:    : not found

In this case, it seems execute commands as control character ( But probably terminal does not output them ).

Execute commands

But you can execute commands without --tty.

echo

echo Alice
Alice
echo Bob
Bob

ls

ls var/lib

apk
misc
udhcpd

exit

exit

Conclusion

On docker interactive mode without tty device, you can execute commands, but it does not behave well as terminal.

Links

• Qiita — Japanese