Scheduling PHP Commands with Cron

Cron invokes scheduled PHP commands in a limited shell environment.

What It Does

Cron invokes scheduled PHP commands in a limited shell environment. The following examples distinguish a normal use case, a boundary case and a practical application.

Requirements and Compatibility

PHP 8.x and a local test environment. Apply input validation, correct error handling and the requirements of any optional libraries.

The code focuses on the core concept. Production implementation may also need routes, validation, persistence, authorization or deployment tooling.

Example 1: Basic Behavior

A sample crontab entry; validate the PHP binary and run permissions.

*/5 * * * * /usr/bin/php /srv/app/bin/cleanup.php >> /var/log/app-cleanup.log 2>&1

This is a command-line example; use it in its appropriate file or shell, not in the PHP source editor.

Example 2: Another Case

A nonblocking process lock prevents duplicate starts on a single host.

<?php
$lock = fopen(sys_get_temp_dir() . '/demo-cron.lock', 'c');
if (!$lock || !flock($lock, LOCK_EX | LOCK_NB)) exit(0);
try { echo 'Task is running'; } finally { flock($lock, LOCK_UN); fclose($lock); }

Practical Example: Putting It to Use

Use explicit time zones and idempotent task design for recurring jobs.

<?php
$now = new DateTimeImmutable('now', new DateTimeZone('UTC'));
echo $now->format(DateTimeInterface::ATOM);

Important Behavior and Edge Cases

Use absolute paths, durable locks and explicit logging to avoid overlapping jobs.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• Cron invokes scheduled PHP commands in a limited shell environment.
• Use absolute paths, durable locks and explicit logging to avoid overlapping jobs.
• Schedulers in queues support retries and distributed locks for more demanding workloads.

Before adapting these examples, verify the return values, test the failure paths and confirm that your application meets its security and environment requirements.