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Running X apps (like zenity) from crontab (solving “cannot open display” problem)

I’ve written a small script that checks whether I have queued mail and that displays a notification icon via “zenity –notification” in case I do. I wanted to run it using ~/.crontab but it wouldn’t run. First, I got error messages from the cron daemon that looked like this:

(zenity:22981): Gtk-WARNING **: cannot open display:

Sure, I hadn’t specified a display. So I tried setting the DISPLAY explicitly in my ~/.crontab:

* * * * export DISPLAY=:0.0 && /path/to/checklog

but then I got:

No protocol specified

(zenity:24101): Gtk-WARNING **: cannot open display: :0

The same happened when I tried running other X apps, like audacious. A line in ~/.crontab like this:

* * * * * DISPLAY=:0 /usr/bin/audacious

resulted in errors like this:

No protocol specified
/usr/bin/audacious: Unable to open display, exiting.

It turns out I needed to set, in my ~/.bashrc:

xhost local:mpromber > /dev/null

to allow crontab access to my X display. It now works, either using “export DISPLAY=:0.0″ in the ~/.crontab, or alternatively just using 

zenity --notification --display=:0.0

in the script that checks for queued mail.

This entry was posted on Friday, January 2nd, 2009 at 19:42 and is filed under Linux, Noobs. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

10 Responses to “Running X apps (like zenity) from crontab (solving “cannot open display” problem)”

  1. man Says:
    March 18th, 2010 at 10:41

    Wow, thanks this was frustrating to get it working.

  2. Hello, Zenity + crontab Says:
    November 4th, 2010 at 14:00

    [...] [...]

  3. Marianne Says:
    November 4th, 2010 at 14:10

    Hi, in reply to the latest pingback (comment #2; I’m not signed up to the forum it links to) — what exactly doesn’t work for you? Note that “mpromber” in this line

    xhost local:mpromber > /dev/null

    is my username, so you’d have to substitute your username.

  4. serpro Says:
    August 18th, 2011 at 19:20

    YOU ARE THE BEST ONE

  5. Pavel Says:
    September 1st, 2011 at 16:53

    Yeah! Thanks a lot! It really works!

  6. Valentin Says:
    October 20th, 2011 at 20:24

    Thanks a lot – I stumbled about this problem, too.

  7. how to accomplished to run zenity in cronjob Says:
    April 2nd, 2012 at 20:37

    [...] thanks for speedy reply I was about to try your suggestion but some how i found this link "Running X app from crontab" what i used was the –diplay=:0.0 option in the zenity which is [...]

  8. How to accomplished to run zenity in cronjob? - The UNIX and Linux Forums Says:
    April 2nd, 2012 at 20:43

    [...] you miss understand me about your answer in the other furom. I found my answer on this link " Running X apps on crontab" what i did was i add the –display=:0.0 option in the zenity [...]

  9. Charles Says:
    April 3rd, 2012 at 04:36

    Using ~/.bashrc for the xhost command is not robust. It will only work if one of the Bash Startup Files for an interactive logon shell sources ~/.bashrc. It is common practice to do so but not universal.

    If xhost is run unconditionally, it will result in an error when the user logs on at a virtual terminal: xhost: unable to open display “”. Making it conditional on $DISPLAY being set avoids this.

    The same code will work for all users by using $LOGNAME instead of a hard-coded user name string.

    Putting this all together, put this in ~/.bash_profile:

    [[ $DISPLAY ]] && xhost +localhost:$LOGNAME

  10. Christya Says:
    May 4th, 2012 at 08:56

    I’m from Russia and you help so much!!! THANKS!!! =)

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