nginx configuration file description

nginx configuration file description
 # nginx running username 
user nginx;
 # nginx starts the process, usually set to be equal to the number of cpu, here is automatic 
worker_processes auto;

# errorlog file location 
error_log / var / log /nginx/error. log ;
 # pid file address, records the pid of nginx, which is convenient for process management 
pid /run/nginx. pid;

# Load dynamic modules. See /usr/share/nginx/README.dynamic. #Configurations 
used to load other dynamic modules 
include /usr/share/nginx/modules /* .conf;

# Working mode and connection limit
events {
    # Maximum number of concurrent connections per worker_processes
    # Total concurrency: worker_processes*worker_connections
    worker_connections 1024;
}

# Some configuration parameters related to providing http services are similar to mail
http {
    # Set the format of the log
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    # access_log records the accessed user, page, browser, ip and other access information
    access_log  /var/log/nginx/access.log  main;

    # This part will be explained separately below
    # Set whether nginx uses the sendfile function to output files
    sendfile            on;
    # Send the packet when the packet is the largest (using the Nagle algorithm)
    tcp_nopush          on;
    # Send packets immediately (disable Nagle algorithm)
    tcp_nodelay         on;
    # link timeout
    keepalive_timeout   65;
    # I don't know about this either...
    types_hash_max_size 2048;

    # Introduce file extension and file type mapping table
    include             /etc/nginx/mime.types;
    # Default file type
    default_type        application/octet-stream;

    # Load modular configuration files from the /etc/nginx/conf.d directory.
    # See http://nginx.org/en/docs/ngx_core_module.html#include
    # for more information.
    include /etc/nginx/conf.d/*.conf;

    # Several virtual hosts are supported on the http service.
    # A corresponding server configuration item for each virtual host
    # The configuration item contains the configuration related to the virtual host.
    server {
        # port
        listen       80 default_server;
        listen       [::]:80 default_server;
        # Visited domain name
        server_name  _;
        # Default website root directory (www directory)
        root         /usr/share/nginx/html;

        # Load configuration files for the default server block.

        include /etc/nginx/default.d/*.conf;

        # default request
        location / {
        }

        # Error page (404)
        error_page 404 /404.html;
            location = /40x.html {
        }

        # Error page (50X)
        error_page 500 502 503 504 /50x.html;
            location = /50x.html {
        }
    }
}

Key points

1. Regarding error_log, you can set the type of log (what level of information to record): debug, info, notice, warn, error, crit

2. About 
the general network transmission process  of sendfile
Hard disk >> kernel buffer >> user buffer >> kernel socket buffer >> protocol stack 
After using sendfile, 
hard disk >> kernel buffer (quick copy to kernelsocket buffer) >> protocol stack 
can significantly improve the transmission performance.

3. tcp_nopush and tcp_nodelay 
tcp_nopush only works when sendfile is 
enabled. After tcp_nopush is enabled, the program will not send the data packet immediately after receiving it, but will wait for the maximum data packet to be sent at one time, which can relieve network congestion. (Nagleization) 
In contrast, tcp_nodelay sends out packets immediately.

server { listen 80 default_server; listen [::]:80 default_server; # This is changed, you can also write your domain name server_name 192.168.17.26; # Default website root directory (www directory) root /var/www/; # Load configuration files for the default server block. include /etc/nginx/default.d/*.conf; location / { # The name of the home page index file is changed here index index.php index.html index.htm; } error_page 404 /404 .html; location = /40x.html { } error_page 500 502 503 504 /50x.html; location = /50x.html { } # The newly added # PHP script requests are all forwarded to FastCGI for processing. The default configuration of the FastCGI protocol is used. # The protocol for communication between the Fastcgi server and the program (PHP, Python). location ~ \.php$ { # Set the listening port fastcgi_pass 127.0.0.1:9000; # Set the default home page file of nginx (it has been set above and can be deleted) fastcgi_index index.php; # Set the path of the script file request fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; # Introduce the configuration file of fastcgi include fastcgi_params; } }