(Docker notes): The difference between CMD and ENTRYPOINT

The difference between CMD and ENTRYPOINT

CMD command

• CMD specifies the command to run when the container is started, only the last one will take effect and will be replaced
  • Create a dockerfile

FROM centos 

CMD ["ls","-a"] 

• Build image

docker build -f dockerfile-cmd-test -t cmdtest .

• To append a -l command, execute the ls -al command

• In the case of CMD, -l replaced the CMD ["ls","-a"] command, but -l is not a command, so an error was reported .

ENTRYPOINT command

• ENTRYPOINT to operate, create a dockerfile

• Build and run

• As shown in the figure above, until this step, the results are no different from using CMD
• Plus -l test
  • You will find that the result is not only correct, but also the same as executing ls -al, so you can see the difference between the two commands
  • Here the -l command is directly spliced ​​after the ENTRYPOINT command