Send an error message to the defined error handling routines

Description

error_log(
    string $message,
    int $message_type = 0,
    ?string $destination = null,
    ?string $additional_headers = null
): bool

Sends an error message to the web server's error log or to a file.

Parameters

message

The error message that should be logged.

message_type

Says where the error should go. The possible message types are as follows:

**error_log()** log types
0	`message` is sent to PHP's system logger, using the Operating System's system logging mechanism or a file, depending on what the error_log configuration directive is set to. This is the default option.
1	`message` is sent by email to the address in the `destination` parameter. This is the only message type where the fourth parameter, `additional_headers` is used.
2	No longer an option.
3	`message` is appended to the file `destination`. A newline is not automatically added to the end of the `message` string.
4	`message` is sent directly to the SAPI logging handler.

destination

The destination. Its meaning depends on the message_type parameter as described above.

additional_headers

The extra headers. It's used when the message_type parameter is set to 1. This message type uses the same internal function as mail() does.

Return Values

Returns true on success or false on failure. If message_type is zero, this function always returns true, regardless of whether the error could be logged or not.

Changelog

Version	Description
8.0.0	`destination` and `additional_headers` are now nullable.

Examples

Example #1 error_log() examples

<?php
// Send notification through the server log if we can not
// connect to the database.
if (!Ora_Logon($username, $password)) {
    error_log("Oracle database not available!", 0);
}

// Notify administrator by email if we run out of FOO
if (!($foo = allocate_new_foo())) {
    error_log("Big trouble, we're all out of FOOs!", 1,
               "operator@example.com");
}

// another way to call error_log():
error_log("You messed up!", 3, "/var/tmp/my-errors.log");
?>

Notes

Warning

error_log() is not binary safe. message will be truncated by null character.

Tip

message should not contain null character. Note that message may be sent to file, mail, syslog, etc. Use appropriate conversion/escape function, base64_encode(), rawurlencode() or addslashes() before calling error_log().