I find when using docker run I sometimes don't need to add a "command", while sometimes a "command" is a must. E.g. when running the ubuntu image a command isn't required:
# docker run ubuntu
#
While when running mstormo/suse:
# docker run mstormo/suse
Error response from daemon: No command specified
# docker run mstormo/suse bash
#
So is this related to the specified image?