Ubuntu – How to run a script when a directory is changed by another user

bashcommand linefilesysteminotifyscripts

I know has been a bit of discussion about topics similar to this. But here is what I am basically trying to do.

I have a watch directory called watched and whenever a file is added to that directory, I want to trigger a script called syncbh.sh which will take files out of that directory and upload them to a remote server.

The caveat is that files are created in the watched directory by one user (user2), but the script is executed by another (user1).

I've tried using incron to accomplish this, but keep running into a major problem because while the script can be executed manually by user1 with root privileges, the incron daemon is never actually automatically triggered by a file creation event by the other user2.

I've thought about whether inoticoming would be a better alternative, but I'm unclear about how the syntax of this works. If there a better way to accomplish this, or if I end up using inoticoming what would the command syntax be to ask it to watch /home/user1/watched directory and execute the script /usr/local/bin/syncbh.sh if a file is created/modified within that directory?

Any help would be much appreciated.

Best Answer

Using inoticoming:

You can put a script in /etc/init.d/ that runs inoticoming at boot time.

Create a new folder to hold the inoticoming log / last pid for the watched folder: sudo mkdir -p /var/log/inoticoming/watched/
Create a script inoticoming_watched in /etc/init.d/:

_{* Remember to change <path_to_folder> and <path_to_script> to match the full path of the watched folder and the full path of the script to execute}

#!/bin/sh

case "${1}" in
    start)
        inoticoming --logfile '/var/log/inoticoming/watched/inoticoming.log' --pid-file '/var/log/inoticoming/watched/inoticoming_last_pid.txt' <path_to_folder> <path_to_script> \;
    ;;

    stop)
        kill -15 $(< /var/log/inoticoming/watched/inoticoming_last_pid.txt tee)
    ;;

    restart)
        ${0} stop
        sleep 1
        ${0} start
    ;;

    *)
    echo "Usage: ${0} {start|stop|restart}"
    exit 1
    ;;
esac

Mark the script as executable: sudo chmod u+x /etc/init.d/inoticoming_watched
Make sure that the script called by inoticoming_watched is executable.
Update rc.d to make the service inoticoming_watched start at boot time: sudo update-rc.d inoticoming_watched defaults

You can check the inoticoming log in /var/log/inoticoming/watched.

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I've just had this using IN_CLOSE_WRITE and finally tracked down the problem. My original script was reading in mail from stdin line by line and then writing each line to the file. This was causing incron to fire on every line write. I saw this based on the number of incron events and how many lines were in the file.

I then changed the original script to read all of stdin in before writing the file. Once this was in place I no longer saw multiple incron executions on the same file.

Ubuntu – How to run a script when the lid is closed

First, I created a new file /etc/acpi/events/laptop-lid containing the following:

event=button/lid.*
action=/etc/acpi/laptop-lid.sh

Then I created /etc/acpi/laptop-lid.sh containing this code:

#!/bin/bash

source /home/michael/.Xdbus
grep -q closed /proc/acpi/button/lid/LID/state
if [ $? = 0 ]
then
    # close action
    dm-tool switch-to-greeter
    sleep 5
    systemctl suspend
else
    # open action
fi

In /home/michael/.Xdbus I put the following:

export XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0

And I made /etc/acpi/laptop-lid.sh executable (chmod a+x).

Then I ran /etc/init.d/acpid restart

Finally, I went into XFCE Power Manager and set it to "Switch off display" when the laptop lid is closed, so as to avoid conflicting with my new, improved functionality.

However, I found there was still a problem - after I came out of suspend, the login screen would be displayed and then the machine would suspend again. After a bit of searching I think this is due to a bug in Ubuntu that apparently still exists in 18.04. I worked around it by checking if more than 6 seconds have passed since I tried to sleep 5 seconds, and if so I don't suspend. It seems like my laptop actually suspends in under 2 seconds, so this is always working for me. I tried setting Xfce to lock the screen, but it didn't seem to honor that either - in both cases, my machine was suspended in under 2 seconds, whereas my script should be forcing it to wait at least 5.

Update:

After doing all of this, I was still totally unsatisfied. Because my XFCE Power Manager settings are basically ignored leading the machine to always sleep when I close the lid, this creates a race condition between the sleep process and how far the dm-tool gets towards creating the greeter, which always results in some delay on resume while that process finishes bringing up the greeter. So I totally undid all of the above work and instead did the following:

Edit ~/.config/openbox/lubuntu-rc.xml. Find the key binding to lock the screen and change it to switch to the greeter instead. The main effect of this seems to be to not turn off the display, which seems important to making the greeter show up instantly on resume:

    <keybind key='W-L'>
        <action name='Execute'>
            <command>dm-tool switch-to-greeter</command>
        </action>
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Now instead of closing the lid, I hit Win+L, and as soon as the greeter appears I then close the lid.

Note: I wanted to have a separate script that first switches to the greeter, then suspends, but it seems like no matter how I try to suspend (systemctl, dbus, etc.) they all refuse to suspend from the lock screen without manual intervention - entering a password from a dialog box - that impossible to satisfy because we are at the lock screen!

Best Answer

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