Certain modules such as
gnrc_icmpv6_echo can expose (some of) their functionality not only as C-API, but also as shell command. Using the module
shell_commands will enable the shell integration of the used modules, if it exists.
A few rarely needed shell commands that needs to be used in addition to the
shell_commands and the module providing the C-API. Examples include
random_cmd. Consult the documentation of the modules to find out whether they have a shell integration and how to enable it.