How do I run a command on an already existing Docker container

Question

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

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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

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Pipe a command to stdin  Must remove the -t for it to work   echo  touch myfile    sudo docker exec -i CONTAINER NAME bash   This can be more convenient that using CLI options sometimes   Tested with   sudo docker run --name ub16 -it ubuntu 16 04 bash   then on another shell   echo  touch myfile    sudo docker exec -i ub16 bash   Then on first shell   ls -l myfile   Tested on Docker 1 13 1  Ubuntu 16 04 host

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I usually use this       docker exec -it my-container-name bash   to continuously interact with a running container

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docker exec -d container id command    Ex     docker exec -d xcdefrdtt service jira stop

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So I think the answer is simpler than many misleading answers above   To start an existing container which is stopped  docker start  lt container-name ID gt    To stop a running container  docker stop  lt container-name ID gt    Then to login to the interactive shell of a container  docker exec -it  lt container-name ID gt  bash   To start an existing container and attach to it in one command  docker start -ai  lt container-name ID gt    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

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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

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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

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A quick way to resume and access the most recently exited container   docker start -a -i  docker ps -q -l

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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

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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

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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

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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

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Simple answer  start and attach at the same time  In this case you are doing exactly what you asked for   docker start  lt CONTAINER ID CONTAINER NAME gt   amp  amp  docker attach  lt CONTAINER ID CONTAINER NAME gt     make sure to change  lt CONTAINER ID CONTAINER NAME gt

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For Mac     docker exec -it  lt container-name gt  sh   if you want to connect as root user     docker exec -u 0 -it  lt container-name gt  sh

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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

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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

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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

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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

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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  lt container id or name gt  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

[docker] How do I run a command on an already existing Docker container?

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