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Rafael Muynarsk
Asked: 2018-05-23 17:56:00 +0800 CST

My script runs fine when I run it from the terminal but it doesn't work with cron. Why?

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I'm creating a script to manage my icons and I'm using the command gvfs-set-attribute in order to do that. The script works fine when I run it with the terminal but it fails to work when I use cron. Here is a simplified version of my problem:

#!/bin/bash

PATH=/home/myUser/bin:/home/myUser/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin:/home/myUser/.local/share/gvfs-metadata

gvfs-set-attribute -t string /home/myUser/myFolder metadata::custom-icon file:///home/myUser/myImage.png

I've used crontab -e and settled my script to run every minute * * * * * /home/myUser/script.bash. The problem is that this script doesn't work at all when I run it with cron.

I've already written the PATH on my script as described in this other issue and the output of the command whereis gvfs-set-attribute is:

gvfs-set-attribute: /usr/bin/gvfs-set-attribute /usr/share/man/man1/gvfs-set-attribute.1.gz

So, I'm assuming there's nothing wrong with the PATH here. I've also tried to run my script directly with the absolute path: /usr/bin/gvfs-set-attribute. But any of those things worked... Does anyone have any idea of what's happening and why I can't use the command gvfs-set-attribute with cron?

icons cron paths gvfs 16.04

2 Answers

  1. cron jobs do not run under the X window system, and do not normally access GUI objects.

    However, you can cheat.

    In a terminal, running under the GUI:

    xhost +localhost

echo "export DISPLAY=\"$DISPLAY\"" >$HOME/.display

    And, near the beginning of the cron job:

    source $HOME/.display

    Read man xhost.

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  2. Best Answer

    Try adding this line to your script (obviously before the call to gvfs-set-attribute):

    export $(cat /proc/$(pgrep gnome-session)/environ | grep -z ^DBUS_SESSION_BUS_ADDRESS)

    It picks up the DBUS_SESSION_BUS_ADDRESS environment variable from your existing gnome-session. This makes two assumptions though:

    1. You are running a gnome-session; and
    2. There is only one gnome-session

    If there are multiple gnome-sessions (i.e. one each for multiple users) you can change this line to work for a specific user by adding the -u option to pgrep. For example:

    export $(cat /proc/$(pgrep gnome-session -u myUser)/environ | grep -z ^DBUS_SESSION_BUS_ADDRESS)

    If you are not using gnome - then I think this will work with other desktop environments by replacing gnome-session with another value - such as lxsession for LXDE.

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