Nginx Cheatsheet

This cheatsheet covers common Nginx commands, configuration structure, directives, and examples, consolidated into a single document.

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Core Commands (Systemd Systems - Ubuntu/Debian/CentOS 7+)

Use sudo before these commands if not running as root.

Command	Description
systemctl start nginx	Start the Nginx service.
systemctl stop nginx	Stop the Nginx service.
systemctl restart nginx	Stop and then start the Nginx service.
systemctl reload nginx	Reload configuration without stopping the server (graceful reload).
systemctl status nginx	Check the current status of the Nginx service.
systemctl enable nginx	Enable Nginx to start automatically on system boot.
systemctl disable nginx	Disable Nginx from starting automatically on system boot.
nginx -t	Test the Nginx configuration files for syntax errors.
nginx -t -c <config_file>	Test a specific configuration file.
nginx -v	Show Nginx version.
nginx -V	Show Nginx version, build parameters, and module information.

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Alternative nginx commands (less common for service management)

Command	Description
nginx -s stop	Fast shutdown.
nginx -s quit	Graceful shutdown.
nginx -s reload	Reload configuration file.
nginx -s reopen	Reopen log files.

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Default File & Directory Locations

Locations can vary depending on installation method (package manager, source) and OS distribution. These are common defaults:

• Main Configuration File:
  • /etc/nginx/nginx.conf (Most Systems)
  • /usr/local/nginx/conf/nginx.conf (Compiled from source default)
• Server Block / Virtual Host Configs:
  • /etc/nginx/sites-available/ (Config files are defined here - Debian/Ubuntu)
  • /etc/nginx/sites-enabled/ (Symlinks to configs in sites-available that should be active - Debian/Ubuntu)
  • /etc/nginx/conf.d/ (Directory for .conf files, often used by CentOS/RHEL and included by nginx.conf)
• Default Web Root:
  • /var/www/html (Debian/Ubuntu)
  • /usr/share/nginx/html (CentOS/RHEL)
• Log Files:
  • /var/log/nginx/access.log (Access logs)
  • /var/log/nginx/error.log (Error logs)
• Nginx Binary:
  • /usr/sbin/nginx
• PID File:
  • /var/run/nginx.pid or /run/nginx.pid

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Configuration File Structure

• Directives: Configuration options (e.g., worker_processes, listen). End with a semicolon ;.
• Blocks / Contexts: Group directives that apply to a certain scope (e.g., http, server, location). Defined by curly braces {}.
• Comments: Lines starting with #.
• Includes: Load configuration from other files using the include directive. Wildcards (*) can be used.

# Example Structure of nginx.conf (simplified)
user www-data; # Directive: Run worker processes as this user
worker_processes auto; # Directive: Auto-detect number of CPU cores for workers
pid /run/nginx.pid; # Directive: File to store the main process ID

# Events block: Connection processing settings
events {
    worker_connections 768; # Max connections per worker process
}

# HTTP block: Defines parameters for HTTP/HTTPS traffic
http {
    # Include MIME types definition
    include       /etc/nginx/mime.types;
    # Default MIME type if none matches
    default_type  application/octet-stream;

    # Define a custom log format named 'main'
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    # Set access log path and use the 'main' format
    access_log  /var/log/nginx/access.log  main;
    # Set error log path and minimum logging level
    error_log   /var/log/nginx/error.log warn;

    # Performance optimizations
    sendfile        on; # Use sendfile() for efficient file serving
    tcp_nopush      on; # Optimize packet sending
    tcp_nodelay     on; # Disable Nagle's algorithm

    # Timeout for keep-alive connections
    keepalive_timeout  65;

    # Enable gzip compression (requires further gzip_* directives typically)
    # gzip            on;

    # Include server block configuration files
    # Common on CentOS/RHEL/Fedora:
    include /etc/nginx/conf.d/*.conf;
    # Common on Debian/Ubuntu:
    include /etc/nginx/sites-enabled/*;

    # Example Server Block (Virtual Host) - often in separate included file
    # server {
    #     listen 80;
    #     server_name example.com www.example.com;
    #
    #     location / {
    #         root   /var/www/html;
    #         index  index.html index.htm;
    #     }
    # }
}