Detailed explanation of the process of building an image server with nginx (the difference between root and alias)

The installation process is omitted (I installed it directly using yum -y install nginx; ).

start up

Start (restart) nginx, the following two commands are OK:

systemctl restart nginx;
# Note: nginx here is not a directory, it is /usr/sbin/nginx -s reload;

Generally, if there is no error, it means the startup is successful.

Verify whether nginx is started on the page

Enter the IP address in the browser and return to the CentOS page. Is this wrong?
Look at the configuration file:

root /usr/share/nginx/html;

The content of index.html in this directory is the content of the centos homepage, which means there is no problem and nignx is started (you can also change the title of index.html to confirm it).

Preparation

mkdir -p /data/images; # Create a directory for storing image files chmod -R 755 /data/images; # Authorize cd /data/images; 
Then use the rz command to upload a picture 01.png

vim /etc/nginx.conf, add configuration:

location /images {
 root /data;
 autoindex on;
}

Browser input:
111.222.333.444/data/images/01.png;
A picture appears, indicating success.

Using alias configuration

Of course, you can also use aliases:

location /images {
 alias /data/images; # It is said that the '/' must be added at the end, but in practice, autoindex on can be run without it;
}

The following writing has problems:

location /images {
 alias /data; 
 autoindex on; 
}

What’s the problem?
Entering /images/01.png in the address bar will not get it.
Because /images will be mapped to /data,
But the actual directory is /data/images/01.png,
So there is one less image.

Misconfiguration

In reality, it may not be that smooth and there will be many pitfalls.

Incorrect configuration example 1 (root)

location /images {
 root /data/images;
 autoindex on;
}

Enter ip/data/images/01.png in the address bar and find that it cannot be obtained. Why?

Expected address:
/data/images/01.png
Physical Address:
/data/images/images/01.png

Found it, there is one more image,
Because root is used, address = root + location

other

The difference between root and alias