error_log message is truncated when using print_r

If you check the error INI options in PHP you'll notice there's a log_errors_max_len option:

Set the maximum length of log_errors in bytes. In error_log information about the source is added. The default is 1024 and 0 allows to not apply any maximum length at all. This length is applied to logged errors, displayed errors and also to $php_errormsg.

When an integer is used, the value is measured in bytes. Shorthand notation, as described in this FAQ, may also be used.

Hence, if you want to use error_log to output these huge messages, make sure you change log_errors_max_len to a large number (or 0 for unlimited length).

// Append to the start of your script
ini_set('log_errors_max_len', '0');

As scrowler mentions its error_log that's limiting the output.

The error_log will log to syslog by default and in your code, the length of which is limited by the runtime setting log_errors_max_len and which is 1024 by default.

See the following for further details on these functions and settings -

http://php.net/manual/en/function.error-log.php http://php.net/manual/en/errorfunc.configuration.php#ini.log-errors-max-len

What you probably want to do is just call print_r ($bigArray) to have it output directly, or if you want to see something a bit fancier in a browser use

echo '<pre>' . print_r ($bigArray, TRUE) . '</pre>';

If a string in the array contains a null character (byte with value zero), the output will also be truncated at that point. From https://secure.php.net/manual/en/function.error-log.php#refsect1-function.error-log-notes:

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

To work around this you could use str_replace to eliminate null characters:

error_log("big array:" . str_replace("\0", '\\0', print_r($bigArray, true)));

This answer is a bit out of date.

The output from error_log will still get truncated, even if log_errors_max_len is set to 0 (for unlimited output).

As per the PHP documentation for log_errors_max_len:

This length is applied to logged errors, displayed errors and also to $php_errormsg, but not to explicitly called functions such as error_log().

The only way to get your error_log() statements to truly output large amounts of information is to specify a custom log file.

error_log("big array:" . print_r($bigArray, true), 3, '/path/to/custom.log');

The second parameter (3) indicates the message type (external log) as per the error_log documentation.