如何在 docker 镜像的新容器中运行 bash？
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How can I run bash in a new container of a docker image?
提问by Lone Learner
I am able to run arbitrary shell commands in a container created from docker/whalesay image.
我能够在从 docker/whalesay 映像创建的容器中运行任意 shell 命令。
$ docker run docker/whalesay ls -l
total 56
-rw-r--r-- 1 root root 931 May 25 2015 ChangeLog
-rw-r--r-- 1 root root 385 May 25 2015 INSTALL
-rw-r--r-- 1 root root 1116 May 25 2015 LICENSE
-rw-r--r-- 1 root root 445 May 25 2015 MANIFEST
-rw-r--r-- 1 root root 1610 May 25 2015 README
-rw-r--r-- 1 root root 879 May 25 2015 Wrap.pm.diff
drwxr-xr-x 2 root root 4096 May 25 2015 cows
-rwxr-xr-x 1 root root 4129 May 25 2015 cowsay
-rw-r--r-- 1 root root 4690 May 25 2015 cowsay.1
-rw-r--r-- 1 root root 54 May 25 2015 install.pl
-rwxr-xr-x 1 root root 2046 May 25 2015 install.sh
-rw-r--r-- 1 root root 631 May 25 2015 pgp_public_key.txt
$ docker run docker/whalesay lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 14.04.2 LTS
Release: 14.04
Codename: trusty
However, I am unable to run a shell in a container created from this image.
但是，我无法在从此映像创建的容器中运行 shell。
$ docker run docker/whalesay bash
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
7ce600cc9904 docker/whalesay "bash" 5 seconds ago Exited (0) 3 seconds ago loving_mayer
Why did it not work? How can I make it work?
为什么它不起作用？我怎样才能让它工作？
回答by Dan Lowe
If you docker runwithout attaching a tty, and only call bash, then bash finds nothing to do, and it exits. That's because by default, a container is non-interactive, and a shell that runs in non-interactive mode expects a script to run. Absent that, it will exit.
如果您docker run没有附加 tty，而只调用bash，那么 bash 将无事可做，然后退出。这是因为默认情况下，容器是非交互式的，并且以非交互式模式运行的 shell 需要运行脚本。如果没有，它将退出。
To run a new container, you can simply attach a tty and standard input:
要运行一个新容器，您只需附加一个 tty 和标准输入：
docker run -it --entrypoint bash <image-name-or-id>
Or to enter a running container, use execinstead:
或者要进入正在运行的容器，请exec改用：
docker exec -it <container-name-or-id> bash
In comments you asked
在你问的评论中
Do you know what is the difference between this and
docker run -it --entrypoint bash docker/whalesay?
你知道这和 有
docker run -it --entrypoint bash docker/whalesay什么区别吗？
In the two commands above, you are specifying bashas the CMD. In this command, you are specifying bashas the ENTRYPOINT.
在上面的两个命令中，您指定bash为CMD. 在此命令中，您指定bash为ENTRYPOINT.
Every container is run using a combination of ENTRYPOINTand CMD. If you (or the image) does not specify ENTRYPOINT, the default entrypoint is /bin/sh -c.
每个容器使用的组合运行ENTRYPOINT和CMD。如果您（或图像）未指定ENTRYPOINT，则默认入口点为/bin/sh -c。
So in the earlier two commands, if you run bashas the CMD, and the default ENTRYPOINTis used, then the container will be run using
所以在前面的两个命令中，如果你bash作为运行CMD，并且使用默认值ENTRYPOINT，那么容器将使用
/bin/sh -c bash
If you specify --entrypoint bash, then instead it runs
如果您指定--entrypoint bash，则它会运行
bash <command>
Where <command>is the CMDspecified in the image (if any is specified).
凡<command>在CMD图像中指定的（如果指定的话）。
