This example illustrates the usage of the [Console Component](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/console.html#console) to create an interactive shell on a ESP chip. The interactive shell running on the ESP chip can then be controlled/interacted with over a serial interface. This example supports UART and USB interfaces.
The interactive shell implemented in this example contains a wide variety of commands, and can act as a basis for applications that require a command-line interface (CLI).
When UART interface is used, this example can run on any commonly available Espressif development board. UART interface is enabled by default (`CONFIG_ESP_CONSOLE_UART_DEFAULT` option in menuconfig). No extra configuration is required.
### Using with USB_SERIAL_JTAG
*NOTE: We recommend to disable the secondary console output on chips with USB_SERIAL_JTAG since the secondary serial is output-only and would not be very useful when using a console application. This is why the secondary console output is deactivated per default (CONFIG_ESP_CONSOLE_SECONDARY_NONE=y)*
On chips with USB_SERIAL_JTAG peripheral, console example can be used over the USB serial port.
* First, connect the USB cable to the USB_SERIAL_JTAG interface.
* Second, run `idf.py menuconfig` and enable `CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG` option.
For more details about connecting and configuring USB_SERIAL_JTAG (including pin numbers), see the IDF Programming Guide:
* Enable/Disable storing command history in flash and load the history in a next example run. Linenoise line editing library provides functions to save and load
command history. If this option is enabled, initializes a FAT filesystem and uses it to store command history.
*`Example Configuration > Store command history in flash`
* Accept/Ignore empty lines inserted into the console. If an empty line is inserted to the console, the Console can either ignore empty lines (the example would continue), or break on emplty lines (the example would stop after an empty line).
*`Example Configuration > Ignore empty lines inserted into the console`
Enter the `help` command get a full list of all available commands. The following is a sample session of the Console Example where a variety of commands provided by the Console Example are used. Note that GPIO15 is connected to GND to remove the boot log output.
The line endings in the Console Example are configured to match particular serial monitors. Therefore, if the following log output appears, consider using a different serial monitor (e.g. Putty for Windows) or modify the example's [UART configuration](#Configuring-UART).
- **Line Endings**: The default line endings are configured to match those expected/generated by common serial monitor programs, such as `screen`, `minicom`, and the `esp-idf-monitor` included in the SDK. The default behavior for these commands are:
- When 'enter' key is pressed on the keyboard, `CR` (0x13) code is sent to the serial device.
- To move the cursor to the beginning of the next line, serial device needs to send `CR LF` (0x13 0x10) sequence.
### Line editing
The main source file of the example illustrates how to use `linenoise` library, including line completion, hints, and history.
### Commands
Several commands are registered using `esp_console_cmd_register()` function. See the `register_wifi()` and `register_system()` functions in `cmd_wifi.c` and `cmd_system.c` files.
### Command handling
Main loop inside `app_main()` function illustrates how to use `linenoise` and `esp_console_run()` to implement read/eval loop.
### Argument parsing
Several commands implemented in `cmd_wifi.c` and `cmd_system.c` use the Argtable3 library to parse and check the arguments.
Each time a new command line is obtained from `linenoise`, it is written into history and the history is saved into a file in flash memory. On reset, history is initialized from that file.
