Raspberry Pi Forums

Posted: **Mon Jan 05, 2015 3:00 pm**

Hi all and Happy New Year,

I am new to Raspberry and Linux so please don't mind silly questions or if this is not the right place to post. I have a Raspberry Pi B+ running Rasbian.

I am trying to create a project whereby when I switch on the Raspberry an .odp presentation starts in presentation mode running in loops (i.e. when it reaches the last slide it starts over). So far so good.

The problem is that I want it to stop after 8 hours....that is, terminate libreoffice using wmctrl -c and then halting the system sudo shutdown -h now.

So I first created a crontab job (i.e. crontab -e) and I added the line:

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*/2 * * * * wmctrl -c libreoffice

. This is every 2 mins for testing purposes. The above line works in terminal but not as a cronjob.
I then created a a script which contained the following lines

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#! bin/bash
wmctrl -c libreoffice

made it executable, placed it in home/pi and changed the crontab

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*/2 * * * * home/pi/killgracefully.sh

. This didn't work either.

I tried other solutions as found at http://stackoverflow.com/questions/1616 ... ind-wmctrl, http://stackoverflow.com/questions/2229 ... b-will-use and http://askubuntu.com/questions/29239/wh ... sh-profile.

Nothing seems to work. Any ideas/suggestions will be very much appreciated.
Extra info: the Pi will not be connected to the network and therefore I will never have correct time hence the every 8 hours cronjob.
Thanks
I also

Posted: **Mon Jan 05, 2015 3:59 pm**

You need to use a full path starting with a slash in crontab.

So something.sh in your home directory would go in as

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*/2 * * * * /home/pi/something.sh

Or /usr/bin/foobarprogram would go in as

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*/30 9-19 * * * /usr/bin/foobarprogram -parameter1 --input_file=/home/pi/file.to.read.goes.here -etc

Posted: **Mon Jan 05, 2015 4:09 pm**

Many thanks for the response.

DougieLawson wrote:You need to use a full path starting with a slash in crontab.

So something.sh in your home directory would go in as
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*/2 * * * * /home/pi/something.sh

I may be mistaken but I think this is the same as the last bit of code I posted above (I forgot to add the backslash but it is in my cronjob)?

Posted: **Mon Jan 05, 2015 4:13 pm**

Yiannis wrote:
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*/2 * * * * home/pi/killgracefully.sh

DougieLawson wrote:
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*/2 * * * * /home/pi/something.sh

Spot the difference !!!
Hint: there's a leading slash [/] in one of those examples that's missing in the other.

Posted: **Mon Jan 05, 2015 4:18 pm**

Seriously, apart from the backslash before home (home Vs /home) I cannot see any difference - and as I said earlier the backslash is included in my actual cronjob just missed it in my post.

Posted: **Mon Jan 05, 2015 5:36 pm**

That's not a backslash [\] it's a (forward) slash [/].

Do you get an email from cron when it fails? Do you get anything logged to /var/log/syslog when it fails?

Posted: **Mon Jan 05, 2015 6:35 pm**

Hi,

Apologies for the silly mistake...yes I meant "/".

I am afraid I don't know where to go to read these mails.
I have left the unit back at work...tomorrow morning I will post the contents of /var/log/syslog.

Again many thanks for the support.

Posted: **Mon Jan 05, 2015 7:20 pm**

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#! bin/bash
wmctrl -c libreoffice

Shebang is also missing forward slash

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#!/bin/bash
wmctrl -c libreoffice

Posted: **Tue Jan 06, 2015 9:36 am**

Hi DirkS,

Again I apologise for the omission of forward slash before "bin" but it is included in my original script (since the Pi is not connected to the net I had to write manually my little scripts here hence the little omissions which I know do not help to the discussion).

The contents of the syslog are as follows:

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Dec 26 00:18:01 raspberrypi /USR/SBIN/CRON[2274]: (pi) CMD (/home/pi/killgracefully.sh)
Dec 26 00:18:01 raspberrypi /USR/SBIN/CRON[2273]: (CRON) info (No MTA installed, discarding output)
Dec 26 00:20:01 raspberrypi /USR/SBIN/CRON[2278]: (pi) CMD (/home/pi/killgracefully.sh)
Dec 26 00:20:01 raspberrypi /USR/SBIN/CRON[2277]: (CRON) info (No MTA installed, discarding output)
Dec 26 00:20:01 raspberrypi /USR/SBIN/CRON[2278]: (pi) CMD (/home/pi/killgracefully.sh)
Dec 26 00:20:01 raspberrypi /USR/SBIN/CRON[2277]: (CRON) info (No MTA installed, discarding output

Any idea?
Thanks

Posted: **Tue Jan 06, 2015 9:39 am**

sudo apt-get install postfix

That gets you a mail transfer agent (MTA) and you'll get email from cron with details of what's run or what's gone wrong. Any echo or printf in your shell script comes back as a line in the resulting email.

Posted: **Tue Jan 06, 2015 9:48 am**

Ok, I will need to take the Pi back home tonight to install it and I will get back to you tomorrow with updates.

Many thanks!

Posted: **Tue Jan 06, 2015 9:59 am**

If you are going to shutdown after terminating libreoffice, why bother terminate libreoffice individually. Why not just use the cronjob to shutdown?

As far as I can tell your use of wmctrl in a cronjob is the problem. The cron environment doesn't know about the x window displays. If you definitely want to end libreoffice before calling shutdown you could also try using pkill instead of wmctrl in the cronjob. pkill doesn't need to know about the windows and can take the process name as a parameter.

Posted: **Tue Jan 06, 2015 10:43 am**

Hi mike_p,

Thanks for your reply.

mike_p wrote:If you are going to shutdown after terminating libreoffice, why bother terminate libreoffice individually. Why not just use the cronjob to shutdown?

I want to go in the morning, switch Pi on, the presentation starts and after 8 hours the presentation is terminated gracefully and the Pi shuts down. If the presentation is just killed, then the next morning I have to "recover" the presentation which means that a mouse/keyboard should be involved. This cannot be done because the monitor will be on a wall, only connected to the Pi and power supply...nothing else.

mike_p wrote:As far as I can tell your use of wmctrl in a cronjob is the problem. The cron environment doesn't know about the x window displays.

I think you are right on that but as per first link in my original post I included

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DISPLAY=:0 &&  /home/pi/wmctrl -c

both in the script and/or in the cronjob but it didn't work.

mike_p wrote:If you definitely want to end libreoffice before calling shutdown you could also try using pkill instead of wmctrl in the cronjob. pkill doesn't need to know about the windows and can take the process name as a parameter.

I think it will have the same effect as kill namely I will have to recover the presentation next time I boot Pi up.

Posted: **Tue Jan 06, 2015 6:29 pm**

I think I might have found the problem.

As I said when Pi starts an .odp presentation starts in full/presentation mode. This is achieved via a .desktop file.
The reason why the

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*/2 * * * *  export DISPLAY=:0 && /home/pi/killgracefully.sh

does not work is because when the killgracefully.sh kicks in (every 2 mins) the .odp is in presentation mode and wmctrl seems to have some issues with it. Indeed, when libreoffice is just "windowed" the cronjob and the script work as expected.

So it's an wmctrl issue and I will dig around but if in the meantime you have any suggestions do please let me know.
Thanks

Posted: **Tue Jan 06, 2015 7:18 pm**

Yiannis wrote:
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*/2 * * * *  export DISPLAY=:0 && /home/pi/killgracefully.sh

Does

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*/2 * * * * DISPLAY=:0 /home/pi/killgracefully.sh

work any better.

Posted: **Thu Jan 08, 2015 4:32 pm**

Hi all,

I think I have solved the problem. I post below the solution. It's perhaps not the cleanest one but at least it works for me and I am not going to touch it

.
I used xdotool to simulate the "Escape" key to exit presentation mode. The script looks like this:

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#!/bin/sh
export DISPLAY=:0
WIN=xdotool getwindowfocus
xdotool windowacitvate $WIN
xdotool windowfocus $WIN
xdotool key "Escape"

The line I added in my crontab:

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*/5 * * * * export DISPLAY=:0 && /home/pi/escape.sh

There is no need to use wmctrl anymore as the "Escape" press exits libreoffice altogether.
Again many thanks to all of you for your valuable input.
P.S. Is there a "Solved" button/feature to mark this thread as solved?

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