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!

Approach 2:

• 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.