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Python Signal Example
From reference/signal.txt
Here is a minimal example program. It uses the “alarm()” function to limit the time spent waiting to open a file; this is useful if the file is for a serial device that may not be turned on, which would normally cause the “os.open()” to hang indefinitely. The solution is to set a 5-second alarm before opening the file; if the operation takes too long, the alarm signal will be sent, and the handler raises an exception.
import signal, os def handler(signum, frame): print('Signal handler called with signal', signum) raise OSError("Couldn't open device!") # Set the signal handler and a 5-second alarm signal.signal(signal.SIGALRM, handler) signal.alarm(5) # This open() may hang indefinitely fd = os.open('/dev/ttyS0', os.O_RDWR) signal.alarm(0) # Disable the alarm