crontab: How to run GUI programs with cron

[henriquemaia]

This is an updated Thread from 5.10. It works on 6.06.


First of all, please refer to this howto (http://ubuntuforums.org/showthread.php?t=102626&highlight=cron) to learn more about crontab.


My motivation to find this out was because there are several radio shows I really like and I was always missing them. As such, I needed something to make amarok play the chosen radio station at specific times. Probably this could be achieved through a more elegant solution, but what is explained here works great. Also, I knew that by learning how to do this, I could use it for many other things.

To accomplish this, you have to edit your crontab:


crontab -eyou can also use a nicer GUI tool to edit crontab, like gnome-schedule or KCron (both available on the repositories).

If you use a GUI tool, please adapt the instructions accordingly. I will explain this using as basis the default crontab editor.

To run a GUI command on cron, you'll have to tell cron what display the program should use. For that you use:


export DISPLAY=:0 The ':0' is the default. If you like the program to run on other display, please change the number accordingly (e.g. :1, :2, etc).

So, you add to what is explained here (http://ubuntuforums.org/showthread.php?t=102626&highlight=cron):


01 04 * * * /usr/bin/somedirectory/somecommandthe export variable, like this:


01 04 * * * export DISPLAY=:0 && /usr/bin/somedirectory/somecommandYou can omit the full path to the application bin. For amarok, you just need to use the 'amarok' command. Works fine both ways.

So, in my case, as I want amarok to play Antena2 (Portuguese classical radio station) at a specific time, I use:


30 16 * * 7 export DISPLAY=:0 && amarok mms://rdp.oninet.pt/antena2 This will make amarok start the Antena2 url every Sunday, at 16:30. But I want also to shut up amarok after the show is finished. So, I use:


0 17 * * 7 export DISPLAY=:0 && amarok -s
This will shut up amarok at 17:00 every Sunday.

(Just a side note - to make amarok play mms urls, you have to set it to use xine engine)

You can use this export trick to the limits of your imagination with every kind of application you want.

Another example that occurs to me is when you neet to use an application for a certain period of time, from 3AM to 9AM, for exemple.


0 3 * * * export DISPLAY=:0 && your_favorite_applicationthat will start your_favorite_application (change this to the command that runs the application you desire) everyday at 3AM. To shut it down, I use:


0 9 * * * killall your_favorite_applicationThis will shut it down at 9AM.

Hope this helps some of you.

If you have more ideas how to use this trick (or how to improve this HowTo), please share with us in this thread.

[TomG]

Thanks a lot !
It started to drive me crazy :)

[Watcher]

That is a very neat trick, thank you! (I was looking earlier for something like that)

[henriquemaia]

To both previous posters, I just like to say that I'm very glad that this HowTo helped you. When I found this, I was going mad trying to accomplish this without success. It's really nice to be able to share knowledge.

[Shay Stephens]

Bravo! Thank you for the info. This helped me a lot!

[nchase]

Thank you SO much. This is one of the most useful threads I've ever found on this forum. I had been trying to find a fix to this problem for weeks, and none of them worked -- except this one.

[kinson]

Hi henriquemaia,

Firstly, thanks for this useful post :) the DISPLAY=:0 did the trick for me. Previously I was wondering why my stuff didn't run :)

Actually, I have a question though.

When you say "DISPLAY" here, are we talking about desktop workspaces? Cause I have a teeny little problem.

I'm trying to run the command:


rhythmbox-client --play-pause"


And it does run. The only problem is, that it launches a new instance of rhythmbox(therefore I have 2 music players). If I directly type the command "rhythmbox-client --play-pause" into the terminal, it just pauses/plays the current instance of rhythmbox, and doesn't create a new instance. Is this caused by the DISPLAY?

Hope you can enlighten me on this :)

Thanks,
Kinson.

[rubberglove]

thanks a million - that did the trick. I was just about to give up altogether...

[yeahthisisrob]

I was just about to give up when I find this... thaanks

[seventynine]

Thanks.

[sidefx2]

I've been going crazy trying to figure out why I can't get deluge working...

I'm trying to schedule my torrents to automatically turn on at night after I sleep, so I have this in my crontab:

41 11 * * * DISPLAY=:0 && /usr/bin/deluge

(The time there is just for testing purposes) basically it seems to execute this command but nothing runs. Anyone have any idea would I could be doing wrong?

[seventynine]

I've been going crazy trying to figure out why I can't get deluge working...

I'm trying to schedule my torrents to automatically turn on at night after I sleep, so I have this in my crontab:

41 11 * * * DISPLAY=:0 && /usr/bin/deluge

(The time there is just for testing purposes) basically it seems to execute this command but nothing runs. Anyone have any idea would I could be doing wrong?

here's my working one:

0 0 * * * export DISPLAY=:0 && deluge #start torrents
0 6 * * * killall -9 deluge #stop torrents


you're just missing "export" in your line, it seems

[sidefx2]

That was the problem, thanks a lot!

[FooAtari]

Is there a way to select which Desktop the application opens on?

I'm using crontab to stop and start klibido and it works great. However I would like to open on Desktop 2 if possible?

Thanks

[henriquemaia]

Is there a way to select which Desktop the application opens on?

I'm using crontab to stop and start klibido and it works great. However I would like to open on Desktop 2 if possible?

Thanks

Just change the

DISPLAY=:0

to the number of the display where you want to run the application.

ex:

DISPLAY=:1

or

DISPLAY=:2

[FooAtari]

Hmmm, Ok, ill try that. When I tried it before Klibido didn't load at all. Maybe I made a mistake though I'll try it again

Ta

[henriquemaia]

Hmmm, Ok, ill try that. When I tried it before Klibido didn't load at all. Maybe I made a mistake though I'll try it again

Ta

On the display you want to run the application, run the following command (from a terminal emulator):


echo $DISPLAYIt will give you something like this, (according to the display you’re running):

:0.0

For instance, I opened another display through issuing a


xinit -- :2and when I ran


echo $DISPLAYI got:

:2.0

[FooAtari]

Ok I get 0.0 on both desktops

Maybe I wasn't clear. I only have one display, maybe workspace is a better word. I want to open Klibido on workspace 2.

[henriquemaia]

Ok I get 0.0 on both desktops

Maybe I wasn't clear. I only have one display, maybe workspace is a better word. I want to open Klibido on workspace 2.

For that you will have to mess with your window manager options or use some software like Devil’s Pie (http://burtonini.com/blog/computers/devilspie). I’m not sure if this helps.

[FooAtari]

I'll figure something out. Thanks for trying :)

[euphemus]

Problem solved - I switched from crond to fcron and I could execute a program with a word - like "firefox" or "kaffeine" or "limewire"

Great - I'll use fcron from now on.

[meg23]

Praise the lord! It works!

[arunprasad13]

hi..i have ubuntu edgy 6.10 ..i m not able to run azureus at a particular time in gui...i have copied the different option which i tried and pasted here.

arun@arun-desktop:/opt/azureus$ sudo crontab -e
crontab: installing new crontab
arun@arun-desktop:/opt/azureus$ sudo crontab -l
# m h dom mon dow command
39 00 * * * export DISPLAY=:0 && ./azureus
arun@arun-desktop:/opt/azureus$ sudo crontab -e
crontab: installing new crontab
arun@arun-desktop:/opt/azureus$ sudo crontab -l
# m h dom mon dow command
41 00 * * * export DISPLAY=:0 && /opt/azureus/azureus
arun@arun-desktop:/opt/azureus$ sudo crontab -e
crontab: installing new crontab
arun@arun-desktop:/opt/azureus$ sudo crontab -l
# m h dom mon dow command
43 00 * * * env DISPLAY=:0.0 /opt/azureus/azureus
arun@arun-desktop:/opt/azureus$ sudo crontab -e
crontab: installing new crontab
arun@arun-desktop:/opt/azureus$ sudo crontab -e
crontab: installing new crontab
arun@arun-desktop:/opt/azureus$ sudo crontab -l
# m h dom mon dow command
45 00 * * * env DISPLAY=:0.0 ./azureus
arun@arun-desktop:/opt/azureus$

pl help

[steve101101]

thanks

[jelevin]

Is there a way to use this even if there isn't a display running (i.e., on a headless server)?

[henriquemaia]

Is there a way to use this even if there isn't a display running (i.e., on a headless server)?

Well, of course. cron main use is precisely that, to be used on servers, headless or not. But probably what you want is on another thread. Try searching for crontab tutorials on these forums.

[sparklyprgs]

Excellent! Bad thing is it took over an hour of pain to find this out but it was worth it in the end.

[coskibukowski]

Just THANKS!

[ccczzx]

Thanks is not enough to express my feelings!
And Thanks all of you!

[thiyagi]

Thanks, was useful..

[rob2468]

export DISPLAY=:0.0 && /usr/bin/gnome-terminal
There is something different between GUI app started from cron and normal ways. In terminal, env variables for example are not the same. Settings set in .bashrc do not work.
What's different between cron and normal ways. I'm curious about it.

[henriquemaia]

export DISPLAY=:0.0 && /usr/bin/gnome-terminal
There is something different between GUI app started from cron and normal ways. In terminal, env variables for example are not the same. Settings set in .bashrc do not work.
What's different between cron and normal ways. I'm curious about it.

If unspecified, they're started as root (or as the cron user). You have to specify the user for it. This will set the proper environment variables.

Example:
11 * * * * your_user_here /path/to/command
<timing> <user> <command>

[noisygecko]

One thing that a lot of people probably don't realize is that you can set environment variables for a specific command by just putting them in front of the line. So, for the example of setting the DISPLAY variable in this thread, you can do this in cron:



0 11 * * * DISPLAY=:0 /usr/bin/gnome-terminal


Just make sure you only put spaces in between the variable setting and the command. It is actually more useful in other cases where you only want to change an environment variable for a specific command.