# Clarity on the crontab settings for the preview generator app

**URL:** <https://help.nextcloud.com/t/clarity-on-the-crontab-settings-for-the-preview-generator-app/6144>\
**Category:** ℹ️ Support\
**Created:** [December 13, 2016, 11:49pm UTC](https://help.nextcloud.com/t/clarity-on-the-crontab-settings-for-the-preview-generator-app/6144 "2016-12-13T23:49:13Z")\
**Posts on this page:** 1\
**Showing post:** 8

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**Author:** ![Akhenaton](https://help.nextcloud.com/user_avatar/help.nextcloud.com/akhenaton/32/158_2.png) [@Akhenaton](https://help.nextcloud.com/u/Akhenaton)\
**Post date:** [December 14, 2016, 2:58pm UTC](https://help.nextcloud.com/t/clarity-on-the-crontab-settings-for-the-preview-generator-app/6144/8 "2016-12-14T14:58:04Z")

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I have installed this preview generator app, but it doesn’t seem to do anything… and is poorly documented, if not at all… 😬

My cron job  
`*/30 * * * * php -f /var/www/nextcloud/occ preview:pre-generate`  
runs without error under the user www-data. (checked in my syslog)

I have remarked that in the “/var/www/nextcloud/apps/previewgenerator/lib/Command” directory, there is 3 possible command :  
DeleteOld  
Generate  
PreGenerate

Is the differences in capital letters and writing of “pre-generate” in the cron and “PreGenerate” in the file could be the problem ?

Also, my /var/www/nextcloud/apps/previewgenerator/appinfo/database.xml seems not updated and the oc\_preview\_generation table in the nextcloud database empty…

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_[View the full topic](https://help.nextcloud.com/t/clarity-on-the-crontab-settings-for-the-preview-generator-app/6144)._