How to Preserve Newline Characters in Journald Logs from PHP Stdout

PHP scripts frequently send logs to standard output (stdout), which systemd-journald then collects. However, improperly handled newline characters can lead to jumbled, unreadable logs. This happens because journald expects newline-delimited entries, and buffering or escaping can disrupt this expectation. This guide shows how to reliably preserve newlines in your PHP logs.

Method 1: Direct Output Manipulation

This method focuses on controlling PHP’s output directly to guarantee newline preservation.

Step 1: Explicit Newline Characters: Always terminate each log message with a newline character. Using PHP_EOL ensures cross-platform compatibility:

echo "This is a log entry" . PHP_EOL;

This ensures journald correctly identifies each message. Omitting the newline often leads to concatenated log lines.

Step 2: Disable Output Buffering: Output buffering can delay or combine messages, interfering with newline handling. Disable it at the script’s start:

if (function_exists('ob_get_level')) {
    while (ob_get_level() > 0) {
        ob_end_flush();
    }
}
ini_set('output_buffering', 'off');
ini_set('implicit_flush', 1);
ob_implicit_flush(1);

This forces immediate flushing, sending each line directly to journald.

Step 3: Direct Journald Output: Run your script directly, avoiding redirection or piping that might alter newlines. If using a systemd service, configure it to send stdout directly to journald:

[Service]
ExecStart=/usr/bin/php /path/to/your_script.php
StandardOutput=journal
StandardError=journal

This ensures unmodified output reaches journald, maintaining newline integrity.

Method 2: Leveraging the Syslog Function

PHP’s syslog() function sends logs directly to the system logger, bypassing stdout and reducing newline issues.

Step 1: Using syslog():

openlog('php-script', LOG_PID | LOG_PERROR, LOG_USER);
syslog(LOG_INFO, "This is a log entry with a newline\nAnother line");
closelog();

Each syslog() call creates a separate journald entry. Note that embedded newlines within a single syslog() call might not be preserved; use separate calls for multi-line entries.

Step 2: Verify Syslog Configuration: Confirm your /etc/rsyslog.conf or journald configuration to ensure appropriate message size limits.

Method 3: Custom Delimiters and Post-Processing (Fallback)

If newline preservation remains challenging, use a custom delimiter and post-process the logs.

Step 1: Custom Delimiter in PHP:

echo "First part of log__LOG_NEWLINE__Second part" . PHP_EOL;

Replace __LOG_NEWLINE__ with your chosen delimiter.

Step 2: Post-Processing: Create a script to replace the delimiter with newlines after journald collection. This is a workaround; prioritize direct newline handling.

Conclusion

Maintaining newline integrity in your PHP journald logs ensures clear, easily-parsed log files. By carefully managing output buffering, utilizing explicit newline characters, or employing the syslog() function, you can reliably preserve log structure and avoid common logging issues. Choosing the appropriate method depends on your specific needs and environment. Prioritize methods 1 and 2 for optimal results.