[03] nginx command

1. work process command

Document address: https://nginx.org/en/docs/http/ngx_http_core_module.html

master_process: Used to specify whether to start the working process.

Syntax master_process on|off;
default master_process on;
position global block

worker_processes: Used to configure the number of worker processes generated by Nginx, which is the key to the concurrent processing service of the Nginx server. Theoretically, the larger the value of worker process, the more concurrent processing it can support, but in fact, the setting of this value is subject to the limitations of the server itself. It is recommended to keep this value consistent with the number of cores of the server CPU.

Syntax worker_processes num/auto;
default 1
position global block
default 
[root@localhost conf]# ps -ef|grep nginx
root 7208 1 0 05:19 ? 00:00:00 nginx: master process ./nginx
nobody 7209 7208 0 05:19 ? 00:00:00 nginx: worker process

If you set worker_processes to 2, you will see the following:

root 7208 1 0 05:19 ? 00:00:00 nginx: master process ./nginx
nobody 7227 7208 0 05:28 ? 00:00:00 nginx: worker process
nobody 7228 7208 0 05:28 ? 00:00:00 nginx: worker process

2. server_name directive

server_name: used to set the virtual host service name.

127.0.0.1, localhost, domain name [www.baidu.com | www.jd.com]

Syntax server_name name …;name can provide multiple spaces separated by spaces
default server_name “”;
location server

There are three ways to configure server_name, namely:

exact match
wildcard match
regular expression match

Configuration method 1: exact match

like:

server {<!-- -->
listen 80;
server_name www.itcast.cn www.itheima.cn;
...
}

Supplementary knowledge points:

hosts is a system file without extension, which can be opened with Notepad and other tools. Its function is to establish an associated “database” between some commonly used website domain names and their corresponding IP addresses. When entering a URL, the system will first automatically search for the corresponding IP address from the hosts file. Once found, the system will open the corresponding web page immediately. If not found, the system will submit the URL to the DNS domain name resolution server for IP address resolution.

windows:C:\Windows\System32\drivers\etc
centos: /etc/hosts

Because the domain name is charged a certain fee, we can modify the hosts file to make some virtual domain names for use. You need to modify the /etc/hosts file to add

vim /etc/hosts
127.0.0.1 www.itcast.cn
127.0.0.1 www.itheima.cn

Configuration method 2: use wildcard configuration

The wildcard character “*” is supported in server_name, but it should be noted that the wildcard character cannot appear in the middle of the domain name, and can only appear in the first or last paragraph, such as:

server {<!-- -->
listen 80;
server_name *.itcast.cn www.itheima.*;
# www.itcast.cn abc.itcast.cn www.itheima.cn www.itheima.com
...
}

The following configuration will report an error

server {<!-- -->
listen 80;
server_name www.*.cn www.itheima.c*
...
}

Configuration 3: Use regular expression configuration

Regular expressions can be used in server_name, and ~ is used as the start tag of the regular expression string.

common regular expressions

code description
^ Match search string start position
$ Match search string end position
. Match any single character except newline \\
\ Escape character, the next character Marked as a special character
[xyz] Character set, matches any specified character
[a-z] Character range, match any character in the specified range
\w Match any of the following characters A-Z a-z 0-9 and underscore, equivalent to [A-Za-z0-9_]
\d Number character matching, equivalent In [0-9]
{n} Match exactly n times
{n ,} Match at least n times
{n,m} Match at least n times and up to m times
* zero or more times, equivalent to {0,}
+ One or more times, equivalent to {1,}
? Zero or one time, equivalent to {0,1}

The configuration is as follows:

server{<!-- -->
        listen 80;
        server_name ~^www\.(\w + )\.com$;
        default_type text/plain;
        return 200 $1 $2 ..;
}
Note that no spaces can be added after ~, and the brackets can take values

Match execution order

Since the server_name directive supports wildcards and regular expressions, in a configuration file containing multiple virtual hosts, a name may be successfully matched by server_name of multiple virtual hosts. When this happens , who will handle the current request?

server{<!-- -->
listen 80;
server_name ~^www\.\w + \.com$;
default_type text/plain;
return 200 'regex_success';
}

server{<!-- -->
listen 80;
server_name www.itheima.*;
default_type text/plain;
return 200 'wildcard_after_success';
}

server{<!-- -->
listen 80;
server_name *.itheima.com;
default_type text/plain;
return 200 'wildcard_before_success';
}

server{<!-- -->
listen 80;
server_name www.itheima.com;
default_type text/plain;
return 200 'exact_success';
}

server{<!-- -->
listen 80 default_server;
server_name_;
default_type text/plain;
return 444 'default_server not found server';
}

in conclusion:

exact_success
wildcard_before_success
wildcard_after_success
regex_success
default_server not found server!!

No1: Exact match server_name

No2: The wildcard matches server_name successfully at the beginning

No3: The wildcard matches server_name successfully at the end

No4: The regular expression matches server_name successfully

No5: Processed by the default default_server, if not specified, the first server will be found by default

3. location

Location syntax

URL: https://nginx.org/en/docs/http/ngx_http_core_module.html#location

Syntax: location [ = | ~ | ~* | ^~ ] uri { ... }
location @name { ... }
Default: -
Context: server, location

1. Attribute introduction:

Without a symbol, it must start with a specified pattern
server {<!-- -->
listen 80;
server_name 127.0.0.1;
location /abc{<!-- -->
default_type text/plain;
return 200 "access success";
}
}
The following visits are all correct
http://192.168.200.133/abc
http://192.168.200.133/abc?p1=TOM
http://192.168.200.133/abc/
http://192.168.200.133/abcdef
= : before being used for uri that does not contain regular expressions, it must match the specified pattern exactly
server {<!-- -->
listen 80;
server_name 127.0.0.1;
location =/abc{<!-- -->
default_type text/plain;
return 200 "access success";
}
}
can be matched to
http://192.168.200.133/abc
http://192.168.200.133/abc?p1=TOM
not match
http://192.168.200.133/abc/
http://192.168.200.133/abcdef
~ : Used to indicate that the current uri contains regular expressions and is case-sensitive
~*: Used to indicate that the current uri contains regular expressions and is not case-sensitive

In other words, if the uri contains a regular expression, it needs to be identified by the above two matches

server {<!-- -->
listen 80;
server_name 127.0.0.1;
location ~^/abc\w${
default_type text/plain;
return 200 "access success";
}
}
server {<!-- -->
listen 80;
server_name 127.0.0.1;
location ~*^/abc\w${
default_type text/plain;
return 200 "access success";
}
}
^~: Used before the uri that does not contain regular expressions, the function is the same as that without symbols, the only difference is that if the pattern matches, then stop searching for other patterns. 
server {<!-- -->
listen 80;
server_name 127.0.0.1;
location ^~/abc{<!-- -->
default_type text/plain;
return 200 "access success";
}
}

2. location matching order

nginx has two layers of directives to match request URIs. The first level is the server command, which uses the domain name, ip and port to do the first-level matching. When a matching server is found, it enters the location matching of this server. Locations are not matched exactly in the order they appear in the configuration file. The request URI will match the location configured in the server according to the following rules.

  1. Look for a location with or without the “=” equal sign parameter that completely matches. If there is a fully matched equal sign location, stop matching, execute the instructions in the location, and do not match other types of locations.
  2. Matches all non-regular expression URI locations (including empty, =, ^~ three parameters). Find the longest location matching the request URI and location URI according to the prefix. If the parameter of the longest location is ^~, stop matching and execute the instructions in the location, otherwise temporarily store the location.
  3. Match the location of the regular expression URI (including , * parameters), and match the location in the order in which it appears in the configuration file. If the first matching locaiton is found, the matching will stop and the location will be executed.
  4. After all regular expressions are matched and there is no matching location, the longest prefix matching location temporarily stored in the second step is executed.
Simply follow this rule:
 = > ^~ > ~ = ~* > longest prefix match > /

4. root, alias

Set the directory root/alias of the requested resource

root: set the root directory of the request

Syntax root path;
default root html;
location http, server, location

path is the path of the root directory where the Nginx server searches for resources after receiving the request.

alias: the URI used to change the location

Syntax alias path;
default –
location location

path is the modified root path.

Both of the above two instructions can be used to specify the path to access resources, so what is the difference between the two?

for example:

(1) Create an images directory under the /usr/local/nginx/html directory, and put a picture mv.png image in the directory

location /images {<!-- -->
root /usr/local/nginx/html;
}

The path to access the image is:

http://192.168.200.133/images/mv.png

(2) If you change root to alias

location /images {<!-- -->
alias /usr/local/nginx/html;
}

If you visit the above address again, a 404 error will appear on the page. If you check the error log, you will find that it is because the address is wrong, so it is verified:

The processing result of root is: root path + location path
/usr/local/nginx/html/images/mv.png
The result of alias processing is: replace the location path with the alias path
/usr/local/nginx/html/images

The path behind the alias needs to be changed to

location /images {<!-- -->
alias /usr/local/nginx/html/images;
}

(3) If the location path ends with /, the alias must also end with /, which is not required by root

Modify the above configuration to

location /images/ {<!-- -->
alias /usr/local/nginx/html/images;
}

There will be problems when accessing. Check the error log or the path is wrong, so you need to add / after the alias

summary:

The processing result of root is: root path + location path
The result of alias processing is: replace the location path with the alias path
alias is the definition of a directory alias, and root is the meaning of the top-level directory.
If the location path ends with /, the alias must also end with /, which is not required by root

5. Other

index directive

index: Set the default homepage of the website

Index can be followed by multiple settings. If no specific resource is specified when accessing, it will be searched sequentially until the first one is found.

for example:

location / {
root /usr/local/nginx/html;
index index.html index.htm;
}
When accessing the location, you can use http://ip:port/. If you do not add any content after the address, you will visit index.html and index.htm in turn by default, and find the first one to return

error_page directive

  • error_page: Set the error page of the website
Syntax index file …;
default index index.html;
location http, server, location
Syntax error_page code … [=[response]] uri;
default –
location http, server, location…

When the corresponding response code appears, how to deal with it.

for example:

(1) You can specify the specific jump address
server {<!-- -->
error_page 404 http://www.itcast.cn;
}
(2) Redirect address can be specified
server{<!-- -->
error_page 404 /50x.html;
error_page 500 502 503 504 /50x.html;
location =/50x.html{<!-- -->
root html;
}
}
(3) Use location’s @ match to complete error message display
server{<!-- -->
error_page 404 @jump_to_error;
location @jump_to_error {<!-- -->
default_type text/plain;
return 404 'Not Found Page...';
}
}

The optional =[response] is used to change the corresponding code to another

server{<!-- -->
error_page 404 =200 /50x.html;
location =/50x.html{<!-- -->
root html;
}
}
In this case, when 404 is returned and the corresponding resource cannot be found, it can be seen on the browser that the final returned status code is 200. This piece needs to be paid attention to. When writing the content after error_page, a space needs to be added after 404, 200 no spaces in front