听 ssh 终端上的击键

Question

I have a Python script that listens to arrow down and arrow up keys and reacts by moving a cursor between some choices. I have achieved this using pynput . It works fine on my machine, but when I try to run it on my Raspberry Pi via SSH, it doesn't work. This is what I see on the terminal:

I have hit the down arrow twice, hence the double ^[[B , and the x cursor should have moved to the last square bracket.

I have seen this issue and it's leading me to think that pynput is not suited for my task. Is there any workaround?

Answer 1

The pynput module monitors the Linux input subsystem, which is for input devices attached to your local machine (keyboards, joysticks, mice, etc). Keystrokes received over an ssh connection aren't handled by the input subsystem, because they're not coming from an input device -- they're just data coming over a network connection.

Rather than relying on pynput , your code should just be monitoring standard input for keystrokes. This will work both when running locally and when running over an ssh connection.

The tricky part is that, as you have shown in your question, cursor movement keys like the down arrow generate multi-character escape sequences. Fortunately, the curses module will handle much of this for you; take a look at this example code :

#!/usr/bin/python

import curses

# get the curses screen window
screen = curses.initscr()

# turn off input echoing
curses.noecho()

# respond to keys immediately (don't wait for enter)
curses.cbreak()

# map arrow keys to special values
screen.keypad(True)

try:
    while True:
        char = screen.getch()
        if char == ord('q'):
            break
        elif char == curses.KEY_RIGHT:
            # print doesn't work with curses, use addstr instead
            screen.addstr(0, 0, 'right')
        elif char == curses.KEY_LEFT:
            screen.addstr(0, 0, 'left ')
        elif char == curses.KEY_UP:
            screen.addstr(0, 0, 'up   ')
        elif char == curses.KEY_DOWN:
            screen.addstr(0, 0, 'down ')
finally:
    # shut down cleanly
    curses.nocbreak()
    screen.keypad(0)
    curses.echo()
    curses.endwin()

Answer 2

If your only goal is to get the key presses registered, sshkeyboard library might be a better choice than curses library as it is simpler to use. It cannot handle drawing to display though.

Installing:

pip install sshkeyboard

Reacting to arrows:

from sshkeyboard import listen_keyboard

def press(key):
    if key == "up":
        print("up pressed")
    elif key == "down":
        print("down pressed")
    elif key == "left":
        print("left pressed")
    elif key == "right":
        print("right pressed")

listen_keyboard(on_press=press)