docker container attach

Estimated reading time: 6 minutes

Description

Attach to a running container

Usage

docker container attach [OPTIONS] CONTAINER

Options

Name, shorthand Default Description
--detach-keys   Override the key sequence for detaching a container
--no-stdin false Do not attach STDIN
--sig-proxy true Proxy all received signals to the process

Parent command

Command Description
docker container Manage containers
Command Description
docker container attach Attach to a running container
docker container commit Create a new image from a container’s changes
docker container cp Copy files/folders between a container and the local filesystem
docker container create Create a new container
docker container diff Inspect changes to files or directories on a container’s filesystem
docker container exec Run a command in a running container
docker container export Export a container’s filesystem as a tar archive
docker container inspect Display detailed information on one or more containers
docker container kill Kill one or more running containers
docker container logs Fetch the logs of a container
docker container ls List containers
docker container pause Pause all processes within one or more containers
docker container port List port mappings or a specific mapping for the container
docker container prune Remove all stopped containers
docker container rename Rename a container
docker container restart Restart one or more containers
docker container rm Remove one or more containers
docker container run Run a command in a new container
docker container start Start one or more stopped containers
docker container stats Display a live stream of container(s) resource usage statistics
docker container stop Stop one or more running containers
docker container top Display the running processes of a container
docker container unpause Unpause all processes within one or more containers
docker container update Update configuration of one or more containers
docker container wait Block until one or more containers stop, then print their exit codes

Extended description

The docker attach command allows you to attach to a running container using the container’s ID or name, either to view its ongoing output or to control it interactively. You can attach to the same contained process multiple times simultaneously, screen sharing style, or quickly view the progress of your detached process.

To stop a container, use CTRL-c. This key sequence sends SIGKILL to the container. You can detach from the container (and leave it running) using a configurable key sequence. The default sequence is CTRL-p CTRL-q. You configure the key sequence using the –detach-keys option or a configuration file. See config-json(5) for documentation on using a configuration file.

It is forbidden to redirect the standard input of a docker attach command while attaching to a tty-enabled container (i.e.: launched with -t).

Override the detach sequence

If you want, you can configure an override the Docker key sequence for detach. This is useful if the Docker default sequence conflicts with key sequence you use for other applications. There are two ways to define your own detach key sequence, as a per-container override or as a configuration property on your entire configuration.

To override the sequence for an individual container, use the --detach-keys="<sequence>" flag with the docker attach command. The format of the <sequence> is either a letter [a-Z], or the ctrl- combined with any of the following:

  • a-z (a single lowercase alpha character )
  • @ (at sign)
  • [ (left bracket)
  • \\ (two backward slashes)
  • _ (underscore)
  • ^ (caret)

These a, ctrl-a, X, or ctrl-\\ values are all examples of valid key sequences. To configure a different configuration default key sequence for all containers, see docker(1).

EXAMPLES

Attaching to a container

In this example the top command is run inside a container, from an image called fedora, in detached mode. The ID from the container is passed into the docker attach command:

# ID=$(sudo docker run -d fedora /usr/bin/top -b)
# sudo docker attach $ID
top - 02:05:52 up  3:05,  0 users,  load average: 0.01, 0.02, 0.05
Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.1%!u(MISSING)s,  0.2%!s(MISSING)y,  0.0%!n(MISSING)i, 99.7%!i(MISSING)d,  0.0%!w(MISSING)a,  0.0%!h(MISSING)i,  0.0%!s(MISSING)i,  0.0%!s(MISSING)t
Mem:    373572k total,   355560k used,    18012k free,    27872k buffers
Swap:   786428k total,        0k used,   786428k free,   221740k cached

PID USER      PR  NI  VIRT  RES  SHR S %!C(MISSING)PU %!M(MISSING)EM    TIME+  COMMAND
1 root      20   0 17200 1116  912 R    0  0.3   0:00.03 top

top - 02:05:55 up  3:05,  0 users,  load average: 0.01, 0.02, 0.05
Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%!u(MISSING)s,  0.2%!s(MISSING)y,  0.0%!n(MISSING)i, 99.8%!i(MISSING)d,  0.0%!w(MISSING)a,  0.0%!h(MISSING)i,  0.0%!s(MISSING)i,  0.0%!s(MISSING)t
Mem:    373572k total,   355244k used,    18328k free,    27872k buffers
Swap:   786428k total,        0k used,   786428k free,   221776k cached

PID USER      PR  NI  VIRT  RES  SHR S %!C(MISSING)PU %!M(MISSING)EM    TIME+  COMMAND
1 root      20   0 17208 1144  932 R    0  0.3   0:00.03 top

Examples

Attaching to a container

In this example the top command is run inside a container, from an image called fedora, in detached mode. The ID from the container is passed into the docker attach command:

$ ID=$(sudo docker run -d fedora /usr/bin/top -b)

$ sudo docker attach $ID
top - 02:05:52 up  3:05,  0 users,  load average: 0.01, 0.02, 0.05
Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.1%us,  0.2%sy,  0.0%ni, 99.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:    373572k total,   355560k used,    18012k free,    27872k buffers
Swap:   786428k total,        0k used,   786428k free,   221740k cached

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
1 root      20   0 17200 1116  912 R    0  0.3   0:00.03 top

top - 02:05:55 up  3:05,  0 users,  load average: 0.01, 0.02, 0.05
Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.0%us,  0.2%sy,  0.0%ni, 99.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:    373572k total,   355244k used,    18328k free,    27872k buffers
Swap:   786428k total,        0k used,   786428k free,   221776k cached

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
1 root      20   0 17208 1144  932 R    0  0.3   0:00.03 top
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