进入docker容器后如果退出容器，容器就会变成Exited的状态，那么如何退出容器让容器不关闭呢？
如果要正常退出不关闭容器，请按Ctrl+P+Q进行退出容器，这一点很重要，请牢记！
以下示例为退出容器但不关闭容器
[root@localhost ~]# docker attach c600c4519fc8
[root@c600c4519fc8 /]# exit
exit
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
c600c4519fc8 centos "/bin/bash" 3 hours ago Exited (0) 1 second ago pensive_jackson
5a7a0d694651 busybox "sh" 20 hours ago Exited (0) 20 hours ago hungry_vaughan
4b0296d18849 hello-world "/hello" 46 hours ago Exited (0) 46 hours ago hopeful_yonath
[root@localhost ~]# docker start pensive_jackson
pensive_jackson
[root@localhost ~]# docker attach c600c4519fc8
Ctrl + P + Q
[root@c600c4519fc8 /]# read escape sequence
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
c600c4519fc8 centos "/bin/bash" 3 hours ago Up 22 seconds pensive_jackson
5a7a0d694651 busybox "sh" 20 hours ago Exited (0) 20 hours ago hungry_vaughan
4b0296d18849 hello-world "/hello" 46 hours ago Exited (0) 46 hours ago hopeful_yonath
事实上我们可以在启动容器的时候就进行配置，加入-d参数来启动容器，当然，这条命令仅限于启动全新的容器，启动关闭的容器是不可以的。
Tips 1
docker run -d: 后台运行容器，并返回容器ID
以下示例为使用docker -d启动容器并退出
[root@localhost ~]# docker run -i -t -d centos /bin/bash
8521b11d5d99535d4cb0080adc5a58a4dd018ecd0751d9945f7da7ab01bec330
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
8521b11d5d99 centos "/bin/bash" 4 seconds ago Up 4 seconds eager_goldwasser
c600c4519fc8 centos "/bin/bash" 3 hours ago Exited (0) 28 seconds ago pensive_jackson
5a7a0d694651 busybox "sh" 20 hours ago Exited (0) 20 hours ago hungry_vaughan
4b0296d18849 hello-world "/hello" 46 hours ago Exited (0) 46 hours ago hopeful_yonath
[root@localhost ~]# docker attach 8
[root@8521b11d5d99 /]# uname -r
3.10.0-514.el7.x86_64
[root@8521b11d5d99 /]# exit
exit
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
8521b11d5d99 centos "/bin/bash" 2 minutes ago Exited (0) 2 seconds ago eager_goldwasser
c600c4519fc8 centos "/bin/bash" 3 hours ago Exited (0) 2 minutes ago pensive_jackson
5a7a0d694651 busybox "sh" 20 hours ago Exited (0) 20 hours ago hungry_vaughan
4b0296d18849 hello-world "/hello" 46 hours ago Exited (0) 46 hours ago hopeful_yonath
在这里你可能会发现，使用了-d的命令退出后容器依然还是死了，动手型的朋友可能会发现只是用docker run -d去启动容器也一样是死的
这里其实需要了解的是容器的运行机制，Docker容器在后台运行，必须要有一个前台进程，这里我们让容器有前台程序运行，就可以实现容器的-d 启动后存活
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
c600c4519fc8 centos "/bin/bash" 3 hours ago Exited (0) 4 minutes ago pensive_jackson
5a7a0d694651 busybox "sh" 21 hours ago Exited (0) 21 hours ago hungry_vaughan
4b0296d18849 hello-world "/hello" 47 hours ago Exited (0) 47 hours ago hopeful_yonath
[root@localhost ~]# docker run -d centos /bin/bash -c "nohup ping -i 1000 www.baidu.com"
8aa19c9604382bc019797ccda831ae1bcebd81d86380b6040d636e03000b440a
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
8aa19c960438 centos "/bin/bash -c 'nohup…" 2 seconds ago Up 2 seconds adoring_wing
c600c4519fc8 centos "/bin/bash" 3 hours ago Exited (0) 5 minutes ago pensive_jackson
5a7a0d694651 busybox "sh" 21 hours ago Exited (0) 21 hours ago hungry_vaughan
4b0296d18849 hello-world "/hello" 47 hours ago Exited (0) 47 hours ago hopeful_yonath
我这里使用nohup在后台运行一个每1000秒ping一次百度的进程，另外你也可以使用"while true; do echo hello world; sleep 1; done"，无限输出hello world。
另外即便是有进程在后台运行，你进入了容器，输入exit退出，依然会终止容器的运行，请谨记。
