Run a PHP script as a daemon

Sun, Dec 15, 2024 2-minute read

Below is a simple example of a PHP script and guidance on how you could run it as a daemon.

Example PHP Script

Create a file called daemon_example.php:

#!/usr/bin/php
<?php

// This script simply writes a timestamp to a log file every 10 seconds.
$logFile = '/tmp/mydaemon.log';

while (true) {
    $timestamp = date('Y-m-d H:i:s');
    file_put_contents($logFile, "Current time: $timestamp\n", FILE_APPEND);
    sleep(10);
}

Key Points About the Script:

It runs an infinite loop.
Every 10 seconds, it appends the current time to the file /tmp/mydaemon.log.
The #!/usr/bin/php shebang line ensures it can be run directly (if the file is executable).

Making the Script Executable

In a terminal, run:

chmod +x daemon_example.php

Now you can run the script directly:

./daemon_example.php

This will start running in the current terminal. To stop it, press Ctrl+C.

Running it as a Daemon

Method 1: Using nohup and & The simplest way to run it as a daemon (background process) is:

nohup ./daemon_example.php > /dev/null 2>&1 &

nohup ensures the process isn’t stopped when you log out.
> /dev/null 2>&1 discards any output to avoid cluttering the terminal.
The & at the end runs it in the background.

You can check if it’s running using:

ps aux | grep daemon_example.php

To stop it, find its process ID (PID) and kill it:

kill <PID>

Method 2: Using systemd (Preferred for Production) If you have root or administrative access and your system uses systemd, you can create a service file to manage your PHP script as a proper daemon.

Create a service file (e.g., /etc/systemd/system/mydaemon.service):

[Unit]
Description=My PHP Daemon Service

[Service]
ExecStart=/usr/bin/php /path/to/daemon_example.php
Restart=always

[Install]
WantedBy=multi-user.target

Reload systemd’s configuration:
```
sudo systemctl daemon-reload
```
Start the service:
```
sudo systemctl start mydaemon.service
```
Enable the service on startup:
```
sudo systemctl enable mydaemon.service
```

Check the status:

sudo systemctl status mydaemon.service

Stop the service:

sudo systemctl stop mydaemon.service

Using systemd provides a more robust solution with automatic restarts, logging integration, and control over the lifecycle of the daemon.

In summary:

Write a PHP script with a continuous loop to perform the desired task.
Make the script executable and run it in the background with nohup or manage it using systemd for a more reliable daemon setup.

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