How to log errors and warnings into a file in php?

In PHP, errors and warnings can be logged into a file by using a php script and changing configuration of php.ini file. Two such approaches are mentioned below:

Approach 1: The error_log() function can be used to send error messages to a given file. First argument to the function is the error message to be sent. Second argument tells where to send/log the error message. In this case, second argument is set to 3, used to redirect error message to a file. Third argument is used to specify the file path of the error logging file.

Below is the implementation of the above approach:

<?php 
// php code for logging error into a given file 
  
// error message to be logged 
$error_message = "This is an error message!"; 
  
// path of the log file where errors need to be logged 
$log_file = "./my-errors.log"; 
  
// logging error message to given log file 
error_log($error_message, 3, $log_file); 
  
?> 

OUTPUT

[20-Dec-2018 17:32:00 UTC] This is an error message!

• The init_set() function allows a user to programmatically update configuration of the php.ini file.
• The ini_set(“log_errors”, TRUE) command can be added to the php script to enable error logging in php.
• The ini_set(‘error_log’, $log_file) command can be added to the php script to set the error logging file.
• Further error_log($error_message) function call can be used to log error message to the given file.

Below is the implementation of the above approach:

<?php 
// PHP code for logging error into a given file 

// error message to be logged 
$error_message = "This is an error message!"; 

// path of the log file where errors need to be logged 
$log_file = "./my-errors.log"; 

// setting error logging to be active 
ini_set("log_errors", TRUE); 

// setting the logging file in php.ini 
ini_set('error_log', $log_file); 

// logging the error 
error_log($error_message); 

?> 

OUTPUT

[20-Dec-2018 17:30:35 UTC] This is an error message!

Similar Approach: Following lines can also be added directly to php.ini to make the configuration changes permanent for every php script that logs errors and warnings.

log_errors = on
error_log = ./errors.log

Note:: This approach is not highly reliable as compared to other approaches. Its better to use approach 1 as it gives flexibility of choosing different files for logging at same time without changing configuration of php.ini file.