What is the difference between docker run and docker exec commands?

Difference: 1. The operation object of "docker run" is "mirror", while the operation object of "docker exec" is "container"; 2. "docker run" is suitable for situations where no container is running, and "docker exec" is suitable for running commands in existing containers.

The operating environment of this tutorial: linux5.9.8 system, docker-1.13.1 version, Dell G3 computer.

The difference between docker run and docker exec

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##docker run:Create a container based on the image and run it A command, the object of the operation is mirror;

docker exec:In the running container When executing the command, the object of the operation is container.

"docker run" is usually the command used in newly created containers. It's suitable for situations where you don't have a container running, and you want to create a container, start it, and then run a process on it.

"docker exec" is suitable for running commands in existing containers. If you already have a running container and want to change it or get something from it, then using the "docker exec" command is perfect.

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docker run command

Syntax

docker run [OPTIONS] IMAGE [COMMAND] [ARG...]

OPTIONS Description:

• -a stdin: Specifies the standard input and output content type, optional STDIN/STDOUT/STDERR;

• -d: Run the container in the background and return the container ID;

• -i: to interact Mode to run the container, usually used with -t;

• -P: Random port mapping, container internal portRandomMapped to the high port of the host

• -p:Specify port mapping, the format is: Host (host) port:Container port

• -t:Reassign a pseudo input terminal to the container, usually used together with -i;

• --name="nginx-lb": Specify a name for the container;

• --dns 8.8.8.8: Specifies the DNS server used by the container, which is consistent with the host by default;

• --dns-search example.com: Specifies the container DNS search domain name, which defaults to the same as the host;

• -h "mars": Specify the hostname of the container;

• -e username ="ritchie": Set environment variables;

• --env-file=[]: From specified The file is read into the environment variable;

• --cpuset="0-2" or --cpuset="0,1,2": Bind the container to the specified CPU to run;

• ##-m:Set the maximum memory used by the container;

• --net="bridge": Specifies the network connection type of the container, supports bridge/host/none/container: four types Type;

• ##--link=[]

  : Add a link to another container;

• --expose=[]

  : Open a port or a group of ports;

• --volume , -v

  : Bind a volume

Instance

Use docker image nginx:latest to start one in background mode container and name the container my-nginx.

docker run --name my-nginx -p 8081:80 -d nginx:latest

The browser accesses http://host IP:8081, the effect is as follows:

##Use mirror nginx: latest starts a container in background mode and maps the container's port 80 to a random port on the host:

docker run -P -d nginx:latest

使用镜像 nginx:latest 以后台模式启动一个容器，将主机的 80 端口映射到容器的 80 端口，主机的目录 /data 映射到容器的 /data：

docker run -p 80:80 -v /data:/data -d nginx:latest

使用镜像 nginx:latest 以交互模式启动一个容器，在容器内执行/bin/bash命令：

docker run -it nginx:latest /bin/bash

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docker exec 命令

语法

docker exec [OPTIONS] CONTAINER COMMAND [ARG...]

OPTIONS说明：

• -d : 分离模式: 在后台运行

• -i :  即使没有附加也保持STDIN 打开

• -t : 分配一个伪终端

在容器名称 my-nginx 中开启一个交互模式的终端：

docker exec -it my-nginx /bin/bash

或者使用容器ID 721eb23901ce 开启一个交互模式的终端：

docker exec -it 721eb23901ce /bin/bash

推荐学习：《docker视频教程》

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