Docker

Entrypoint and CMD

Each commands executed in ENTRYPOINT and CMD has a PID 1. For instance:

FROM ubuntu
# ENTRYPOINT ["/bin/sleep", "120"]
CMD ["/bin/sleep", "60"]

And we build the Docker and execute it:

$ docker build -t test .
Sending build context to Docker daemon  2.048kB
Step 1/2 : FROM ubuntu
 ---> 602eb6fb314b
Step 2/2 : CMD ["/bin/sleep", "60"]
 ---> Using cache
 ---> a647c5903c6c
Successfully built a647c5903c6c
Successfully tagged test:latest
$ docker run test &
$ docker exec -it e1584c04298c bash
root@e1584c04298c:/# ps auxf
USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root           8  1.2  0.0   4588  3912 pts/0    Ss   14:56   0:00 bash
root          16  0.0  0.0   7888  3964 pts/0    R+   14:56   0:00  \_ ps auxf
root           1  0.0  0.0   2696  1072 ?        Ss   14:55   0:00 /bin/sleep 60