However, there's an alternative approach to find out what key was pressed when `signal_handler()` was fired: using signal handling mechanisms that allow you to store information about the signal and then retrieve it after the signal has been handled.
In Python, you can use the `signal.signal` function to specify a custom handler for each signal. Here's an example:
python
import signal
def my_signal_handler(signum, frame):
# You can access the signal number here
print(f"Received signal {signum}")
# Register our custom handler for SIGINT (Ctrl+C)
signal.signal(signal.SIGINT, my_signal_handler)
print("Press Ctrl+C to exit...")
When you run this program and press Ctrl+C, it will print out the signal number `SIGINT` instead of just "Received signal <number>". The `<number>` is not a specific key code but rather a unique identifier for the signal.
Unfortunately, there's no way to access which key was pressed when a SIGINT (Ctrl+C) or any other keyboard interrupt occurs without using some kind of operating system-specific or platform-dependent function that's not available in standard Python.
On Linux and macOS, you can use the `readline` library to read input from the terminal, including key presses. Here's an example:
python
import sys
def my_signal_handler(signum, frame):
# We're still in the handler for SIGINT here.
print("SIGINT caught")
# Register our custom handler for SIGINT (Ctrl+C)
signal.signal(signal.SIGINT, my_signal_handler)
print("Press Ctrl+C to exit...")
And then you can modify your program as follows:
python
import sys
def handle_input(prompt):
while True:
input_str = input(prompt)
if not input_str:
break
# You can do something with the input here.
try:
handle_input("Enter some text: ")
except KeyboardInterrupt:
print("\nReceived Ctrl+C, exiting.")
In this case, you won't get a key press event in standard Python because it's too low-level. However, by using `readline`, you can read from the terminal and detect keyboard events.
If you're on Windows, you'll need to use the `msvcrt` library or another platform-specific library that provides access to the underlying operating system's keyboard APIs.
python
import msvcrt
def my_signal_handler(signum, frame):
# We're still in the handler for SIGINT here.
print("SIGINT caught")
# Register our custom handler for SIGINT (Ctrl+C)
signal.signal(signal.SIGINT, my_signal_handler)
while True:
if msvcrt.kbhit():
key = msvcrt.getch()
if key == b'\x03': # Ctrl+C
break