Debugging in PHP and Wordpress

Question

@ini_set('log_errors','On'); and define('WP_DEBUG', true);

I'm trying to create a error log file , but i'm confusing about these two. what kind of errors will get by log_errors and WP_DEBUG ?

Answer 1

The define('WP_DEBUG_LOG', true); will log errors into the debug.log file in the wp-content directory, @ini_set('log_errors','On'); allows you to specify the file where you want to save it. This should work for you:

@ini_set('log_errors', 1);
@ini_set('display_errors', 0); /* enable or disable public display of errors (use 'On' or 'Off') */
@ini_set('error_log', dirname(__FILE__) . '/wp-content/logs/your-error-file.log'); /* path to server-writable log file */
@ini_set( 'error_reporting', E_ALL ^ E_NOTICE ); /* the php parser to  all errors, excreportept notices.  */

Answer 2

The @ini_set('log_errors','On'); option sets the PHP handler to log errors. It is a general configuration option used to control script's behaviour. More on the function here

The define('WP_DEBUG', true); on the other hand is very WP specific, it is used to capture and either print to screen / write to file WP specific errors. More on it here.

Writing to a log file

1. PHP

PHP stores error logs in /var/log/apache2 if PHP is an Apache2 module. Shared hosts are often store log files in your root directory /log subfolder.

If you have access to a php.ini file you can specify the path like this:

error_log = /var/log/custom-logging-script.log

2. WordPress

You can tell WP to log entries to a file by setting define( 'WP_DEBUG_LOG', true ); . That causes all errors to also be saved to a debug.log log file inside the /wp-content/ directory.

3. Alternately

If you quickly want to inspect a function or a variable then try something like this error_log($my_error, 3, "/var/tmp/my-errors.log");. Its a handy function, more details here.

What you use depends on your requirement and what you want to debug.