docker pull httpd
..
docker run -d --name MyWebServer httpd
..
docker attach MyWebServer
(nothing printed here - so I press enter + ls)
ls
(nothing printed here - so I press enter multiple times and still nothing..)
When I try to do the same thing with ubuntu image, it works. Why it isn't working here?
The difference is the running process. With Ubuntu, you are being attached to the sh. With httpd you are being attached to the apache main process, which is not a shell.
Do this instead of attach:
docker exec -it MyWebServer sh
With that, you are launching a shell inside the same container that runs apache process.
Have you read the docs? The attach returns any messages that the container produces. I bet you wanted to do the exec instead.
It’s either
docker exec -it container_name_or_id bash
or
docker-compose exec service_name bash
if you use the docker-compose app.
You can execute any command (unless the container has no fixed entrypoint), for instance
docker exec container ls /
I have following Dockerfile:
FROM elixir:1.4.5
COPY . /
RUN mix compile
CMD echo "Application started" && elixir --name $MY_POD_NAMESPACE#$MY_POD_IP --no-halt --cookie $ERLANG_COOKIE -S mix run
It starts and runs well, but when I try either attatch or exec XXX bash it does not respond at all.
Both the commands are different as such
docker attach containerid gets your to main process which was running and if it doesn't output anything further then you will not see anything. You should rather use docker logs containerid to see the output of your code
docker exec containerId bash means you want to get to a bash process inside the container. This command would execute and end immediately as you have not specified the interactive and the tty flags. Update it to use it as below
docker exec -it containerId bash
And you should be able to get a bash. If it still doesn't work then use docker stats containerId to see what kind of CPU and memory usage your container has
If docker exec -it container-id bash doesn't work then try docker exec -it container-id sh
Sometimes bash command doesn't work.
I have a python script that loads my db with a bunch of data and thus takes a long while for it to run. Because of this if I run...
$ docker exec -d CONTAINER python /path/to/myscript.py
Was curious if it is possible to run
$ docker exec -it CONTAINER /bin/bash
$ root#container-hash /# ps -ax
And see if that process is still running?
You can connect to your docker container via exec as long as the python script has not finished yet. When it is done, the container will be stopped and you can't connect any more.
As long as it is running, you can use docker logs CONTAINER to show the output of your container, if any.
I have a script run.sh that I run as I initialize the container through docker run command. The script runs successfully. I can also get a bash instance (through docker exec -i -t container-name bash) in the container and run the script successfully (note that by default I have su privileges when I get the bash).
However, when I run the script from the host through docker exec -i -t container-name /run.sh the script runs but does not provide the outcome that it provides through the alternative approaches. I know it runs as it produces some of the expected behavior but not all of them. So my main question is what are the difference between executing a script through commandline and running the same script through docker exec.
I created a container with -d so it's not interactive.
docker run -d shykes/pybuilder bin/bash
I see that the container has exited:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d6c45e8cc5f0 shykes/pybuilder:latest "bin/bash" 41 minutes ago Exited (0) 2 seconds ago clever_bardeen
Now I would like to run occasional commands on the machine and exit. Just to get the response.
I tried to start the machine. I tried attaching. I thought I could call run with a container, but that does not seem to be allowed. Using start just seems to run and then exist quickly.
I'd like to get back into interactive mode after exiting.
I tried:
docker attach d6c45e8cc5f0
But I get:
2014/10/01 22:33:34 You cannot attach to a stopped container, start it first
But if I start it, it exits anyway. Catch 22. I can't win.
In October 2014 the Docker team introduced docker exec command: https://docs.docker.com/engine/reference/commandline/exec/
So now you can run any command in a running container just knowing its ID (or name):
docker exec -it <container_id_or_name> echo "Hello from container!"
Note that exec command works only on already running container. If the container is currently stopped, you need to first run it with the following command:
docker run -it -d shykes/pybuilder /bin/bash
The most important thing here is the -d option, which stands for detached. It means that the command you initially provided to the container (/bin/bash) will be run in the background and the container will not stop immediately.
Your container will exit as the command you gave it will end. Use the following options to keep it live:
-i Keep STDIN open even if not attached.
-t Allocate a pseudo-TTY.
So your new run command is:
docker run -it -d shykes/pybuilder bin/bash
If you would like to attach to an already running container:
docker exec -it CONTAINER_ID /bin/bash
In these examples /bin/bash is used as the command.
So I think the answer is simpler than many misleading answers above.
To start an existing container which is stopped
docker start <container-name/ID>
To stop a running container
docker stop <container-name/ID>
Then to login to the interactive shell of a container
docker exec -it <container-name/ID> bash
To start an existing container and attach to it in one command
docker start -ai <container-name/ID>
Beware, this will stop the container on exit. But in general, you need to start the container, attach and stop it after you are done.
To expand on katrmr's answer, if the container is stopped and can't be started due to an error, you'll need to commit it to an image. Then you can launch bash in the new image:
docker commit [CONTAINER_ID] temporary_image
docker run --entrypoint=bash -it temporary_image
Some of the answers here are misleading because they concern containers that are running, not stopped.
Sven Dowideit explained on the Docker forum that containers are bound to their process (and Docker can't change the process of a stopped container, seemingly due at least to its internal structure: https://github.com/docker/docker/issues/1437). So, basically the only option is to commit the container to an image and run it with a different command.
See https://forums.docker.com/t/run-command-in-stopped-container/343
(I believe the "ENTRYPOINT with arguments" approach wouldn't work either, since you still wouldn't be able to change the arguments to a stopped container.)
I had to use bash -c to run my command:
docker exec -it CONTAINER_ID bash -c "mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql mysql"
Creating a container and sending commands to it, one by one:
docker create --name=my_new_container -it ubuntu
docker start my_new_container
// ps -a says 'Up X seconds'
docker exec my_new_container /path/to/my/command
// ps -a still says 'Up X+Y seconds'
docker exec my_new_container /path/to/another/command
If you are trying to run shell script, you need run it as bash.
docker exec -it containerid bash -c /path/to/your/script.sh
This is a combined answer I made up using the CDR LDN answer above and the answer I found here.
The following example starts an Arch Linux container from an image, and then installs git on that container using the pacman tool:
sudo docker run -it -d archlinux /bin/bash
sudo docker ps -l
sudo docker exec -it [container_ID] script /dev/null -c "pacman -S git --noconfirm"
That is all.
Pipe a command to docker exec bash stdin
Must remove the -t for it to work:
echo 'touch myfile' | docker exec -i CONTAINER_NAME bash
This can be more convenient that using CLI options sometimes.
Tested with:
docker run --name ub16 -it ubuntu:16.04 bash
then on another shell:
echo 'touch myfile' | docker exec -i ub16 bash
Then on first shell:
ls -l myfile
Tested on Docker 1.13.1, Ubuntu 16.04 host.
I would like to note that the top answer is a little misleading.
The issue with executing docker run is that a new container is created every time. However, there are cases where we would like to revisit old containers or not take up space with new containers.
(Given clever_bardeen is the name of the container created...)
In OP's case, make sure the docker image is first running by executing the following command:
docker start clever_bardeen
Then, execute the docker container using the following command:
docker exec -it clever_bardeen /bin/bash
I usually use this:
docker exec -it my-container-name bash
to continuously interact with a running container.
Assuming the image is using the default entrypoint /bin/sh -c, running /bin/bash will exit immediately in daemon mode (-d). If you want this container to run an interactive shell, use -it instead of -d. If you want to execute arbitrary commands in a container usually executing another process, you might want to try nsenter or nsinit. Have a look at https://blog.codecentric.de/en/2014/07/enter-docker-container/ for the details.
Unfortunately it is impossible to override ENTRYPOINT with arguments with docker run --entrypoint to achieve this goal.
Note: you can override the ENTRYPOINT setting using --entrypoint, but
this can only set the binary to exec (no sh -c will be used).
For Mac:
$ docker exec -it <container-name> sh
if you want to connect as root user:
$ docker exec -u 0 -it <container-name> sh
Simple answer: start and attach at the same time. In this case you are doing exactly what you asked for.
docker start <CONTAINER_ID/CONTAINER_NAME> && docker attach <CONTAINER_ID/CONTAINER_NAME>
make sure to change <CONTAINER_ID/CONTAINER_NAME>
I am running windows container and I need to look inside the docker container for files and folder created and copied.
In order to do that I used following docker entrypoint command to get the command prompt running inside the container or attach to the container.
ENTRYPOINT ["C:\\Windows\\System32\\cmd.exe", "-D", "FOREGROUND"]
That helped me both to the command prompt attach to container and to keep the container a live. :)
# docker exec -d container_id command
Ex:
# docker exec -d xcdefrdtt service jira stop
A quick way to resume and access the most recently exited container:
docker start -a -i `docker ps -q -l`
An easy solution that solved a similar problem for me:
docker run --interactive --tty <name_of_image>