docker attach 和 docker exec 的区别 [英] difference between docker attach and docker exec

问题描述

两者都可以在容器中执行命令.两者都可以分离容器.

Both will be able to execute commands in container. Both could detach the container.

那么 docker exec 和 docker attach 之间的真正区别是什么?

So what is the real difference between docker exec and docker attach?

推荐答案

有一个 commit PR 添加到文档中:

There was a commit PR which added to the doc:

注意:此命令 (attach) 不适用于在容器中运行新进程.请参阅:docker exec.

Note: This command (attach) is not for running a new process in a container. See: docker exec.

Docker 的答案.如何在运行的容器中获取 bashssh (run -d)?" 说明了区别:

The answer to "Docker. How to get bashssh inside runned container (run -d)?" illustrates the difference:

(docker >= 1.3) 如果我们使用 docker attach，我们只能使用一个shell实例.
因此，如果我们想使用容器外壳的新实例打开新终端，我们只需要运行 docker exec

(docker >= 1.3) If we use docker attach, we can use only one instance of shell.
So if we want to open new terminal with new instance of container's shell, we just need to run docker exec

如果docker容器是使用/bin/bash命令启动的，你可以使用attach来访问它，如果不是那么你需要执行命令来创建一个bash使用 exec 在容器内的实例.

if the docker container was started using /bin/bash command, you can access it using attach, if not then you need to execute the command to create a bash instance inside the container using exec.

如这个问题中所述:

• Attach 不是为了在容器中运行额外的东西，而是为了附加到正在运行的进程.
• "docker exec" 专门用于在已经启动的容器中运行新事物，无论是外壳还是其他一些进程.

• Attach isn't for running an extra thing in a container, it's for attaching to the running process.
• "docker exec" is specifically for running new things in a already started container, be it a shell or some other process.

同样的问题补充:

虽然 attach 没有很好的命名，特别是因为 LXC 命令 lxc-attach(它更类似于 docker exec /bin/sh，但特定于 LXC)，它确实有一个特定的目的，即从字面上将您附加到 Docker 启动的进程中.
根据进程的不同，行为可能会有所不同，例如附加到 /bin/bash 会给你一个 shell，但附加到 redis-server 会像你'd 只是直接启动了 redis，没有进行守护进程.

While attach is not well named, particularly because of the LXC command lxc-attach (which is more akin docker exec <container> /bin/sh, but LXC specific), it does have a specific purpose of literally attaching you to the process Docker started.
Depending on what the process is the behavior may be different, for instance attaching to /bin/bash will give you a shell, but attaching to redis-server will be like you'd just started redis directly without daemonizing.

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