I've just learned about a really cool command for Raspbian OS, available in recent (Debian 9.0 based and later) Raspbian OS releases: pinout command shows you a visual presentation of what hardware configuration your Raspberry Pi has.
Simply type pinout, you don't even need to use sudo. You'll see output consisting of 3 parts that are so visual that I'll screenshot two of them to show you exactly what to expect.
Pinout command for Rasbian OS – Raspberry Pi schematics
First part of the otuput looks really cool – it shows you the model name and the system board layout – where power and HDMI connections, where Ethernet port is and where to plug in USB:
Then you get the second part of the output, which is additional hardware info about your Raspberry Pi:
Revision : a01041 SoC : BCM2836 RAM : 1024Mb Storage : MicroSD USB ports : 4 (excluding power) Ethernet ports : 1 Wi-fi : False Bluetooth : False Camera ports (CSI) : 1 Display ports (DSI): 1
Finally, the last part of the output of the pinout command is actually the pinouts layout for the GPIO part of Raspberry Pi plaform: