why docker container gives different name when using bash to login

Question

docker exec -it xxx /bin/bash some containers give: root@ba5b2a06ef27:/usr/src/myapp# some containers have bash-4.2#. I have compared the output of env, both hostname is a combination of number and letters. But just the login one is root@xxxx, the other one is bash-4.2#. why

Answer 1

It just depends on the particular image & its configuration (specifically the PS1 environment variable).

For example you can start a container using an Ubuntu image that has the environment variable set to the value bash-4.2#. Another container may be using exactly the same version of Ubuntu, but the PS1 environment variable may be set to something different.