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Bash script to start 'motion' on screen lock

rated 0 times [ 1] [ 0] / answers: 1 / hits: 1725 / 1 Year ago, mon, november 14, 2022, 7:11:28

I wish to write a bash script that executes on start up Ubuntu 13.04 and starts motion whenever the screen is locked. Being a novice at bash scripting, I wasn't able to understand the various help sources available on the web and thereby write a script on my own. Anyways, I know that the following command is used to check if the system is locked:

gnome-screensaver-command -q | grep "is active"

But, if I use this command, I will have to periodically (say every 5-10 seconds) check the lock status. Is there a better alternative? Could someone provide me with a skeleton of the script?

So I could write the following script which starts the webcam once I lock the screen but does not stop it once sign back in. Any suggestions?

#!/bin/bash



while :

do

    sleep 2

    if (gnome-screensaver-command -q | grep "is active");

    then

        motion 2> ~/.motion/log

    elif (gnome-screensaver-command -q | grep "is inactive");

    then

        /etc/init.d/motion stop 1> /dev/null

    fi

done

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nuehan

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4 Years ago

answered 1 Year ago ormlai · Accepted Answer

I don't think that you can find a simple better alternative at gnome-screensaver-command -q command, but I found a solution to make your script to function as probably you expect:

#!/bin/bash



is_active=0



while :

do

    sleep 2

    if (gnome-screensaver-command -q | grep "is active");

    then

        if [ "$is_active" -eq "0" ];

        then

            is_active=1

            motion 2> ~/.motion/log &

        fi

    elif (gnome-screensaver-command -q | grep "is inactive");

    then

        if [ "$is_active" -eq "1" ];

        then

            is_active=0

            /etc/init.d/motion stop 1> /dev/null

        fi

    fi

done

Some explanation:

motion 2> ~/.motion/log command followed by & will start the motion process to run in terminal; without &, when the execution of the script reach to that line, this will remain hanged/blocked there.

you don't need to run at every 2 seconds motion 2> ~/.motion/log & or /etc/init.d/motion stop 1> /dev/null command, but only when the state of the screensaver is changing; for this reason other changes from the script.