I am (finally) migrating our Drupal 7 sites to Drupal 10.
The one problem I have not been able to resolve is output from the hook_cron().
Everything appears to execute, whether running on the browser using the special link, clicking on the 'Run cron' button, or as a crontab job. (This is verified by the logger messages, or informational messages which will subsequently appear on the site.)
However, none of the PHP output (for example, echo or print_r()) which worked under Drupal 7 appear on the browser or as an external crontab task. The web page doesn't even refresh. This is problematic because our cronjobs output a lot of debug information that allow us to verify that the tasks ran correctly, and this output is redirected into an email which can be reviewed without accessing the Drupal site. So it is not practical to use the logger or other Drupal mechanisms.
Interestingly, there are scenarios where the output does appear, which might provide a clue as to what the problem is:
- if I include a call to phpinfo()
- on certain (but not all) PHP errors, which causes all preceding output to appear
Note that this issue also occurs with the example cron code (cron_example.module) if I try to add echo statements; I have found one other user (on the drupal forum) who also ran into this as part of other questions, but there was no any information on how to resolve it.
I tried flush() in case it's some sort of buffering issue, but to no avail.
function cron_daily_cron() { // This output is not shown. echo "cron_daily_cron started..."; // The messenger message is shown. \Drupal::logger('cron_daily')->notice('cron_daily_cron started'); \Drupal::messenger()->addMessage('cron_daily_cron started...', 'info'); \Drupal::logger('cron_daily')->notice('cron_daily_cron exited'); // The error output caused by the following line is shown. inexistentfunctioncall(); // This message is not shown. echo "cron_daily_cron exited";}thank you!