In OpenStack, commands correspond to the OpenStack components. For example, the nova command applies to compute operations, cinder to storage, and neutron to networking.
To obtain help on the use of these commands such as the correct syntax, supported subcommands, possible options, and so on, use the command-component help command, such as nova help or neutron help. You can filter the list of possible subcommands to use with the command-component command by using the grep command. For example, to list neutron subcommands that are related to routers, you would type the following command:
# neutron help | grep router l3-agent-list-hosting-router List L3 agents hosting a router. l3-agent-router-add Add a router to a L3 agent. l3-agent-router-remove Remove a router from a L3 agent. net-gateway-connect Add an internal network interface to a router. router-create Create a router for a given tenant. router-delete Delete a given router. router-gateway-clear Remove an external network gateway from a router. router-gateway-set Set the external network gateway for a router. router-interface-add Add an internal network interface to a router. router-interface-delete Remove an internal network interface from a router. router-list List routers that belong to a given tenant. router-list-on-l3-agent List the routers on a L3 agent. router-port-list List ports that belong to a given tenant, with specified router. router-show Show information of a given router. router-update Update router's information.
Then, to obtain specific details about a subcommand, such as router-list which identifies routers in the cloud, you would type the following command:
# neutron help router-list