screen connects your terminal to a remote shell or REPL(like MicroPython) running on the serial port.
screen /dev/tty.SLAB_USBtoUART 115200 connects to a REPL running on an ESP. (Different devices uses different ports.)
To quit screen, press ⌃A+k+y . This leaves my terminal messed up where programs that print line feeds just do the line feed w/out the carriage return. The reset command fixes this.
Using the REPL:
⌃D reboots the board. This will run boot.py and then main.py. If one of these files contains an infinite loop(for example, to run a web server or to continuously print or upload sensor values), you won't see the >>> prompt again. In this case, press ⌃C to get back to the prompt.
ampy
ampy is a command-line tool that manipulates the file system.
Install pip3 install -u adafruit-ampy
ampy -p /dev/tty.SLAB_USBtoUART put file.py copies a file from the host current directory to an ESP.
rshell
rshell opens an interactive shell with commands that support the functionality of both screen and ampy.
Install pip3 install -u adafruit-ampy
rshell -p /dev/tty.SLAB_USBtoUART creates an rshell connection.
rshell may be unable to connect, if the MCU is running a loop that doesn’t return to the MicroPython prompt.(I think it hangs at Testing if ubinascii.unhexlify exists.) In this case, use screen(above) to connect, press ⌃C to quit the MicroPython prompt(you should then see the >>> prompt), quit screen, and try rshell again.
While running rshell, you have access to these commands:
repl opens an Python REPL.
ls /pyboard lists installed files.
rsync . /pyboard copies new and changed files from the current host directory to the MCU.
The micropython-lib repository(as of 8.14.2019) documents some packages that are present, at least, on the ESP8266/EPS32 boards, and not documented in the main MicroPython documentation:
MicroPython on the ESP8266/ESP32
ampy
rshell
Documentation Links