SOLVED: Assigning other signals like SIGUSR1 to keyboard

[Hove]

I'm essentially looking for the fewest keystrokes way to send a SIGUSR1 to an application - ideally from the same console the application is running.

Best solution would be to set up a console keystroke to send a SIGUSR1 to a blocking console application like Ctrl-C sends SIGINT. However I can't find anything from googling.

As an alternative I know I could go to a different console window, and use something along the lines of

Code: Select all

pkill -INT -f "python /home/pi/Downloads/drone.py"

Is there a way to assign that to a keystroke or is the only option to turn it into a 1 line bash script?

Any other suggestions?

[joan]

Create a script containing

sudo killall $1 -USR1

and then invoke the script.

[Joe Schmoe]

Create a script containing

sudo killall $1 -USR1

and then invoke the script.

See .sig.

To the OP: Sometimes (as in this case), the answer is "No."

One way to achieve what (I think) you are trying to achieve might be to setup your app to respond to SIGQUIT (which is usually unused and available - the primary purpose of SIGQUIT is to generate core dump files). SIGQUIT can be generated from the keyboard (and the key bound to it can be set with "stty").

[Hove]

Problem solved but not by assigning other keyboard signals;

The underlying problem, which I tried to distill as much as possible to make the post as small as possible, is that my code uses subprocess.Popen to start up raspivid. Hitting Ctrl-C for my code is caught in a signal handler and does "stuff". Sadly, it's also passed to raspivid as my child, which stops videoing.

Hence this question was about changing the signal sent to my code to do "stuff" without stopping raspivid.

I couldn't daemonize it simply by setting the subprocess.Popen command line to end with "&" - it moaned at that.

But then I discovered the preexec_fn for subprocess.Popen which allowed me to call os.setpgrp() in the preexec_fn, thus separating raspivid from my code's group, and therefore Ctrl-C doesn't get forwarded to raspvid. I can still send raspivid SIGINT in my code when I want to stop the videoing by doing

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def daemonize():
        os.setpgrp()

raspivid_proc = subprocess.Popen(["raspivid", "-o", "video_file_name", "-t", "0"], preexec_fn = daemonize)

....

raspivid_proc.send_signal(signal.SIGINT)

Thanks for the suggested solutions to the distilled problem I described.