Docker学习(18)——CMD和ENTRYPOINT的区别

最新推荐文章于 2025-05-15 16:42:55 发布

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最新推荐文章于 2025-05-15 16:42:55 发布

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分类专栏： Docker 文章标签： docker

本文链接：https://blog.youkuaiyun.com/www_dong/article/details/120687153

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（1）创建dockerfile

[root@192 DockerFile]# touch dockerfile_cmd_test
[root@192 DockerFile]# chmod 755 dockerfile_cmd_test 
[root@192 DockerFile]# vi dockerfile_cmd_test 
[root@192 DockerFile]# cat dockerfile_cmd_test 
FROM centos 
CMD ["ls", "-a"]
[root@192 DockerFile]#

（2）构建镜像

[root@192 DockerFile]# docker build -f dockerfile_cmd_test -t cmd-test .
Sending build context to Docker daemon  3.072kB
Step 1/2 : FROM centos
 ---> 5d0da3dc9764
Step 2/2 : CMD ["ls", "-a"]
 ---> Running in c5d3d5fe0318
Removing intermediate container c5d3d5fe0318
 ---> 255ea4c024a9
Successfully built 255ea4c024a9
Successfully tagged cmd-test:latest
[root@192 DockerFile]#

（3）运行

[root@192 DockerFile]# docker images
REPOSITORY            TAG       IMAGE ID       CREATED          SIZE
cmd-test              latest    255ea4c024a9   59 seconds ago   231MB
[root@192 DockerFile]# docker run 255ea4c024a9
.
..
.dockerenv
bin
dev
etc
home
lib
lib64
lost+found
media
mnt
opt
proc
root
run
sbin
srv
sys
tmp
usr
var
[root@192 DockerFile]#

（4）命令追加

[root@192 DockerFile]# docker run 255ea4c024a9 -l
docker: Error response from daemon: OCI runtime create failed: container_linux.go:380: starting container process caused: exec: "-l": executable file not found in $PATH: unknown.
ERRO[0000] error waiting for container: context canceled 
[root@192 DockerFile]# docker run 255ea4c024a9 ls -al

问题原因：

追加-l命令情况下，替换了CMD ["ls", "-a"]命令，所以报错。可用docker run 255ea4c024a9 ls -al替换。

（5）修改dockerfile

[root@192 DockerFile]# touch dockerfile_entrypoint_test
[root@192 DockerFile]# chmod 755 dockerfile_entrypoint_test 
[root@192 DockerFile]# vi dockerfile_entrypoint_test 
[root@192 DockerFile]# cat dockerfile_entrypoint_test 
FROM centos
ENTRYPOINT ["ls", "-a"]                 ------------------注释：修改命令为ENTRYPOINT 
[root@192 DockerFile]# docker build -f dockerfile_entrypoint_test -t entrypoint_test .
Sending build context to Docker daemon  4.096kB
Step 1/2 : FROM centos
 ---> 5d0da3dc9764
Step 2/2 : ENTRYPOINT ["ls", "-a"]
 ---> Running in 4ac184383032
Removing intermediate container 4ac184383032
 ---> c11fd9dffad1
Successfully built c11fd9dffad1
Successfully tagged entrypoint_test:latest
[root@192 DockerFile]# docker images
REPOSITORY            TAG       IMAGE ID       CREATED         SIZE
entrypoint_test       latest    c11fd9dffad1   8 seconds ago   231MB
[root@192 DockerFile]# docker run c11fd9dffad1 -l    -------注释：可直接追加命令执行
total 0
drwxr-xr-x   1 root root   6 Oct 10 07:43 .
drwxr-xr-x   1 root root   6 Oct 10 07:43 ..
-rwxr-xr-x   1 root root   0 Oct 10 07:43 .dockerenv
lrwxrwxrwx   1 root root   7 Nov  3  2020 bin -> usr/bin
drwxr-xr-x   5 root root 340 Oct 10 07:43 dev
drwxr-xr-x   1 root root  66 Oct 10 07:43 etc
drwxr-xr-x   2 root root   6 Nov  3  2020 home
lrwxrwxrwx   1 root root   7 Nov  3  2020 lib -> usr/lib
lrwxrwxrwx   1 root root   9 Nov  3  2020 lib64 -> usr/lib64
drwx------   2 root root   6 Sep 15 14:17 lost+found
drwxr-xr-x   2 root root   6 Nov  3  2020 media
drwxr-xr-x   2 root root   6 Nov  3  2020 mnt
drwxr-xr-x   2 root root   6 Nov  3  2020 opt
dr-xr-xr-x 246 root root   0 Oct 10 07:43 proc
dr-xr-x---   2 root root 162 Sep 15 14:17 root
drwxr-xr-x  11 root root 163 Sep 15 14:17 run
lrwxrwxrwx   1 root root   8 Nov  3  2020 sbin -> usr/sbin
drwxr-xr-x   2 root root   6 Nov  3  2020 srv
dr-xr-xr-x  13 root root   0 Oct 10 07:39 sys
drwxrwxrwt   7 root root 171 Sep 15 14:17 tmp
drwxr-xr-x  12 root root 144 Sep 15 14:17 usr
drwxr-xr-x  20 root root 262 Sep 15 14:17 var
[root@192 DockerFile]#