Make sure drush is installed (you may also need to make sure the dblog module is enabled) and use:
drush watchdog-show --tail
Available in drush v8 and below.
This will give you a live look at the logs from your console.
We can use drush command also to check logs
drush watchdog-show it will show recent 10 messages.
or if we want to continue showing logs with more information we can user
drush watchdog-show --tail --full.
We came across many situation where we need to check error and error logs to figure out issue we are facing we can check by possibly following method:
1.) On blank screen Some time we got nothing but blank screen instead of our site or message written The website encountered an unexpected error. Please try again later , so we can Print Errors to the Screen by adding
error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);
in index.php at top.;
2.) We should enable optional core module for Database Logging at /admin/build/modules, and then we can check logs your_domain_name/admin/reports/dblog
3.) We can use drush command also to check logs drush watchdog-show it will show recent ten message
or if we want to continue showing logs with more information we can user
drush watchdog-show --tail --full.
4.) Also we can enable core Syslog module this module logs events of operating system of any web server.
If you love the command line, you can also do this using drush with the watchdog show command:
drush ws
More information about this command available here:
To view entries in Drupal's own internal log system (the watchdog database table), go to http://example.com/admin/reports/dblog. These can include Drupal-specific errors as well as general PHP or MySQL errors that have been thrown.
Use the watchdog() function to add an entry to this log from your own custom module.
When Drupal bootstraps it uses the PHP function set_error_handler() to set its own error handler for PHP errors. Therefore, whenever a PHP error occurs within Drupal it will be logged through the watchdog() call at admin/reports/dblog. If you look for PHP fatal errors, for example, in /var/log/apache/error.log and don't see them, this is why. Other errors, e.g. Apache errors, should still be logged in /var/log, or wherever you have it configured to log to.
Source: Stackoverflow.com