nginx.conf — The Master Configuration File¶

What Is It?¶

/etc/nginx/nginx.conf is the main configuration file for Nginx. It is the first file Nginx reads when it starts. Everything about how Nginx behaves globally is defined here.

Where Is It?¶

/etc/nginx/nginx.conf        ← works on both Ubuntu and CentOS

What Does It Look Like?¶

Here is a simplified version of what you will find inside:

user www-data;                        # Which system user runs Nginx
worker_processes auto;                # How many CPU cores to use

error_log /var/log/nginx/error.log;  # Where to write error logs
pid /run/nginx.pid;                   # File that stores Nginx's process ID

events {
    worker_connections 1024;          # Max simultaneous connections per worker
}

http {
    include /etc/nginx/mime.types;    # File type definitions (html, css, jpg, etc.)
    default_type application/octet-stream;

    access_log /var/log/nginx/access.log;  # Where to log all requests

    sendfile on;
    keepalive_timeout 65;

    # This line is what connects nginx.conf to your actual site configs
    include /etc/nginx/sites-enabled/*;    # Ubuntu/Debian
    # include /etc/nginx/conf.d/*.conf;    # CentOS/RHEL
}

Breaking Down Each Section¶

user¶

Defines which Linux system user runs the Nginx worker processes. On Ubuntu this is www-data. On CentOS it is nginx. This matters for file permissions — the web root folder must be readable by this user.

worker_processes auto¶

Tells Nginx how many worker processes to create. auto means use one process per CPU core. More workers = handles more traffic.

events { worker_connections 1024; }¶

Each worker process can handle up to 1024 simultaneous connections. Total capacity = worker_processes × worker_connections.

http { ... }¶

Everything inside here defines how Nginx handles HTTP traffic. This is where your website configuration lives.

include /etc/nginx/sites-enabled/*;¶

This is the most important line. Instead of putting all site configurations inside nginx.conf directly, Nginx reads separate files from sites-enabled/. This keeps things organized — each website gets its own file.

When Do You Edit nginx.conf?¶

You edit nginx.conf when you want to change global behavior: - Increase the number of worker processes - Change log file paths - Tune performance settings - Configure global SSL settings

For individual website configuration, you use sites-enabled/ instead.