How do you attach and detach from Docker s process

Question

I can attach to a docker process but Ctrl c doesn t work to detach from it  exit basically halts the process    What s the recommended workflow to have the process running  occasionally attaching to it to make some changes  and then detaching

User · Answer

Check out also the --sig-proxy option   docker attach --sig-proxy false 304f5db405ec   Then use CTRL c to detach

User · Answer

In the same shell  hold ctrl key and press keys p then q

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Open a new terminal Find the running container Id docker ps Kill the container docker kill   containerId

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To detach from a running container  use  P Q  hold Ctrl  press P  press Q  release Ctrl   There s a catch  this only works if the container was started with both -t and -i  If you have a running container that was started without one  or both  of these options  and you attach with docker attach  you ll need to find another way to detach   Depending on the options you chose and the program that s running   C may work  or it may kill the whole container   You ll have to experiment  Another catch  Depending on the programs you re using  your terminal  shell  SSH client  or multiplexer could be intercepting either  P or  Q  usually the latter    To test whether this is the issue  try running or attaching with the --detach-keys z argument   You should now be able to detach by pressing z  without any modifiers   If this works  another program is interfering   The easiest way to work around this is to set your own detach sequence using the --detach-keys argument    For example  to exit with  K  use --detach-keys  ctrl-k     Alternatively  you can attempt to disable interception of the keys in your terminal or other interfering program   For example  stty start    or stty start undef may prevent the terminal from intercepting  Q on some POSIX systems  though I haven t found this to be helpful

User · Answer

I think this should depend on the situation Take the following container as an example       docker run -it -d ubuntu 91262536f7c9a3060641448120bda7af5ca812b0beb8f3c9fe72811a61db07fc   docker ps CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES 91262536f7c9        ubuntu                bin bash          5 seconds ago       Up 4 seconds                            serene goldstine    1  Use  docker attach  to attach the container     Since  docker attach  will not allocate a new tty  but reuse the original running tty  so if you run exit command  it will cause the running container exit       docker attach 91262536f7c9 exit exit   docker ps -a CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                     PORTS               NAMES 91262536f7c9        ubuntu                bin bash          39 minutes ago      Exited  0  3 seconds ago                       serene goldstine   So unless you really want to make running container exit  you should use Ctrl p   Ctrl q      2  Use  docker exec   Since  docker exec  will allocate a new tty  so I think you should use exit instead of Ctrl p   Ctrl q     The following is executing Ctrl p   Ctrl q to quit the container       docker exec -it 91262536f7c9 bash root 91262536f7c9    ps -aux USER       PID  CPU  MEM    VSZ   RSS TTY      STAT START   TIME COMMAND root         1  0 0  0 0  18160  1908          Ss   04 03   0 00  bin bash root        15  0 0  0 0  18164  1892          Ss   04 03   0 00 bash root        28  0 0  0 0  15564  1148          R    04 03   0 00 ps -aux root 91262536f7c9    echo    15   Then login container again  you will see the bash process in preavious docker exec command is still alive  PID is 15        docker exec -it 91262536f7c9 bash root 91262536f7c9    ps -aux USER       PID  CPU  MEM    VSZ   RSS TTY      STAT START   TIME COMMAND root         1  0 0  0 0  18160  1908          Ss   04 03   0 00  bin bash root        15  0 0  0 0  18164  1892          Ss   04 03   0 00 bash root        29  0 0  0 0  18164  1888          Ss   04 04   0 00 bash root        42  0 0  0 0  15564  1148          R    04 04   0 00 ps -aux root 91262536f7c9    echo    29

User · Answer

I had the same issue  ctrl-P and Q would not work  nor ctrl-C    eventually I opened another terminal session and I did  docker stop containerid   and  docker  start containerid   and it got the job done  Weird

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If you only need the docker process to go in the background you can use  Ctrl   Z  Be aware that it is not a real detach and it comes with a performance penalty   You can return it to foreground with the bg command    Another option is to just close your terminal  if you don t need it any longer

User · Answer

to stop a docker process and release the ports  first use ctrl-c to leave the exit the container then use docker ps to find the list of running containers  Then you can use the docker container stop  to stop that process and release its ports  The container name you can find from the docker ps command which gives the name in the name column  Hope this solves your queries

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I m on a Mac  and for some reason  Ctrl-p Ctrl-q would only work if I also held Shift

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To detach from the container you simply hold Ctrl and press P   Q   To attach to a running container you use     docker container attach  container name

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For anyone who ran into the same problem I did  can t detach without killing the container  even when setting the detach key         When starting your containers with docker-compose up -d   instead of using docker attach  container name  to view the tailing log       try docker-compose logs -f  service name   ctrl-c kills the log tail without killing your container   service name  being the service listed in side of your docker-compose yml file    e g  while container name elk logstash 1 -  service name logstash  HTH

User · Answer

If you just want to make some modification to files or inspect processes  here s one another solution you probably want   You could run the following command to execute a new process from the existing container   sudo docker exec -ti  CONTAINER-ID  bash  will start a new process with bash shell  and you could escape from it by Ctrl C directly  it won t affect the original process

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when nothing else works  open a new terminal then     ps aux   grep attach username   lt pid here gt                     0 00 docker attach  lt CONTAINER HASH HERE gt  username   lt another pid gt                  0 00 grep --color auto attach   kill -9  lt pid here gt

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Update  I typically used docker attach to see what STDOUT was displaying  for troubleshooting containers  I just found docker logs --follow 621a4334f97b  which lets me see the STDOUT whilst also being able to ctrl c off of it without affecting container operation  Exactly what I ve always wanted       naturally you ll need to substitue in your own container ID   Original Answer  I wanted to leave the container running  but had attached without starting the container with -it  My solution was to sacrifice my SSH connection instead  since I was SSHed into the machine that was running the containers   Killing that ssh session left the container intact but detached me from it

User · Answer

To detach the tty without exiting the shell  use the escape sequence Ctrl P followed by Ctrl Q  More details here   Additional info from this source    docker run -t -i   can be detached with  P Qand reattached with docker attach docker run -i   cannot be detached with  P Q  will disrupt stdin docker run   cannot be detached with  P Q  can SIGKILL client  can reattach with docker attach

[docker] How do you attach and detach from Docker's process?

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