111 lines
3.2 KiB
Markdown
111 lines
3.2 KiB
Markdown
---
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title: "exec"
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description: "The exec command description and usage"
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keywords: "command, container, run, execute"
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---
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<!-- This file is maintained within the docker/cli GitHub
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# exec
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```markdown
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Usage: docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
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Run a command in a running container
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Options:
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-d, --detach Detached mode: run command in the background
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--detach-keys Override the key sequence for detaching a container
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-e, --env=[] Set environment variables
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--help Print usage
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-i, --interactive Keep STDIN open even if not attached
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--privileged Give extended privileges to the command
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-t, --tty Allocate a pseudo-TTY
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-u, --user Username or UID (format: <name|uid>[:<group|gid>])
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```
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## Description
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The `docker exec` command runs a new command in a running container.
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The command started using `docker exec` only runs while the container's primary
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process (`PID 1`) is running, and it is not restarted if the container is
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restarted.
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COMMAND will run in the default directory of the container. It the
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underlying image has a custom directory specified with the WORKDIR directive
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in its Dockerfile, this will be used instead.
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COMMAND should be an executable, a chained or a quoted command
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will not work. Example: `docker exec -ti my_container "echo a && echo b"` will
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not work, but `docker exec -ti my_container sh -c "echo a && echo b"` will.
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## Examples
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### Run `docker exec` on a running container
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First, start a container.
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```bash
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$ docker run --name ubuntu_bash --rm -i -t ubuntu bash
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```
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This will create a container named `ubuntu_bash` and start a Bash session.
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Next, execute a command on the container.
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```bash
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$ docker exec -d ubuntu_bash touch /tmp/execWorks
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```
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This will create a new file `/tmp/execWorks` inside the running container
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`ubuntu_bash`, in the background.
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Next, execute an interactive `bash` shell on the container.
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```bash
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$ docker exec -it ubuntu_bash bash
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```
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This will create a new Bash session in the container `ubuntu_bash`.
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Next, set an environment variable in the current bash session.
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```bash
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$ docker exec -it -e VAR=1 ubuntu_bash bash
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```
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This will create a new Bash session in the container `ubuntu_bash` with environment
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variable `$VAR` set to "1". Note that this environment variable will only be valid
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on the current Bash session.
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### Try to run `docker exec` on a paused container
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If the container is paused, then the `docker exec` command will fail with an error:
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```bash
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$ docker pause test
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test
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$ docker ps
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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1ae3b36715d2 ubuntu:latest "bash" 17 seconds ago Up 16 seconds (Paused) test
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$ docker exec test ls
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FATA[0000] Error response from daemon: Container test is paused, unpause the container before exec
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$ echo $?
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1
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```
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