NuttX RTOS is full of features that few people know that exist, mainly because these features were added during it development and none documentation was created to explain about it.

What I will report here what happened with a friend of mine. He was trying to get telnet working on his board, but instead of showing the “nsh> ” prompt to let him access the NuttX terminal he was receiving something completely different:

uIP command shell -- NuttX style
Type '?' and return for help
uIP 1.0> 

After some time he realized that he selected the incorrect telnetd in the menuconfig. He selected CONFIG_EXAMPLES_TELNETD instead of CONFIG_NETUTILS_TELNETD !!!

Then after some time that he fixed that I realized that telnetd example actually is an way to create custom board configuration over telnet, without enabling the more powerful “nsh> “. It avoids security risks!

After realizing it I decided that it was better to make its function clear to let people to extend it, now it will present this message:

Device Configuration over Telnet
You can add functions to setup your device
Type '?' and press <enter> for help
cfg>

Now its purpose is clear and reveal a new feature that was “hidden” on NuttX.