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int_ua
Asked: 2015-06-25 23:23:34 +0800 CST

What code is executed when headphones are disconnected?

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I want to execute a script on headphones disconnect but I resent the idea of constant polling of the status when there is already some code executed when it's changed.

headphones

2 Answers

  1. Best Answer

    In most systems if not all, ACPI can handle this event. To test that:

    1. Run acpi_listen

    2. Unplug & replug headphones, example output: (mic/ears share in same jack on my laptop)

      jack/headphone HEADPHONE unplug
jack/microphone MICROPHONE unplug
jack/headphone HEADPHONE plug
jack/microphone MICROPHONE plug

    3. Put your-script.sh in /etc/acpi/

    4. Add an event trigger file for your script in /etc/acpi/events/

      event=jack/headphone HEADPHONE unplug
action=/etc/acpi/your-script.sh

      Check the other files there to learn from.

    5. You may need to restart acpid service to reload changed rules in /etc/acpi/events/

      sudo service acpid restart

    Reference: man acpid

    • 12

  2. The current version of your script now contains a sleep 0.25 command.

    sleep is timer-based so doesn't use any processing cycles while sleeping…

    It does use a very tiny bit of CPU to set up the timer, but sleep 1 (sleep 1 second), sleep 60 (sleep for a minute) and sleep 86400 (sleep for a day) all use the same number CPU cycles.

    Using ACPI however is the perfect solution as ACPI is event-driven instead of polling-driven.

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