Python • Re: How do I get crontab to run a Python program

@thagrol
Thank you once again.

At least I have an error message now, as follows:

Code:

[13:06:28.101739323] [891171] [1;32m INFO [1;37mCamera [1;34mcamera_manager.cpp:330 [0mlibcamera v0.5.2+99-bfd68f78[13:06:28.142915903] [891226] [1;32m INFO [1;37mIPAProxy [1;34mipa_proxy.cpp:180 [0mUsing tuning file /usr/share/libcamera/ipa/rpi/vc4/imx219.json[13:06:28.156452125] [891226] [1;32m INFO [1;37mCamera [1;34mcamera_manager.cpp:220 [0mAdding camera '/base/soc/i2c0mux/i2c@1/imx219@10' for pipeline handler rpi/vc4[13:06:28.156621812] [891226] [1;32m INFO [1;37mRPI [1;34mvc4.cpp:440 [0mRegistered camera /base/soc/i2c0mux/i2c@1/imx219@10 to Unicam device /dev/media3 and ISP device /dev/media0[13:06:28.156708843] [891226] [1;32m INFO [1;37mRPI [1;34mpipeline_base.cpp:1107 [0mUsing configuration file '/usr/share/libcamera/pipeline/rpi/vc4/rpi_apps.yaml'qt.qpa.xcb: could not connect to display qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.Available platform plugins are: eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb.Aborted

My limited knowledge suggests this has something to do with a Qt platform plug, xcb, that is not available to crontab but is either available when I run the program 'normally', or is not required for normal running.
Using crontab (which I have been using for years) is a lot easier on older pi's with an older OS!

It can't find the x display, try DISPLAY=:0 /path/to/program

Statistics: Posted by thagrol — Fri Oct 17, 2025 11:48 am