Index directive in Nginx - Step-by-Step Execution

Process Flow - Index directive

Client requests URL

↓

Check if URL is directory

Yes↓

Look for index files in order

↓

Serve index file

No↓

Return directory listing or error

When a client requests a directory URL, nginx checks for index files in the order specified by the index directive and serves the first one found.

Execution Sample

Nginx

location / {
    index index.html index.htm index.php;
}

This configuration tells nginx to look for index.html first, then index.htm, then index.php when a directory is requested.

Process Table

Step	Action	Index Files Checked	File Found	Result
1	Client requests /about/	index.html	No	Check next index file
2	Check index.htm	index.htm	No	Check next index file
3	Check index.php	index.php	Yes	Serve index.php file
4	End	-	-	Request served with index.php

💡 index.php found, so nginx serves this file and stops checking further.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
Current Index File	index.html	index.htm	index.php	index.php	index.php
File Found	No	No	Yes	Yes	Yes

Key Moments - 2 Insights

Why does nginx check multiple index files instead of just one?

Because the index directive lists files in order, nginx tries each until it finds one that exists, as shown in execution_table steps 1 to 3.

What happens if none of the index files exist?

Nginx will either show a directory listing or return an error, but this is not shown in the current execution because index.php was found at step 3.

Visual Quiz - 3 Questions

Look at the execution_table, which index file is served to the client?

A index.php

B index.htm

C index.html

D No index file served

💡 Hint

Check the 'File Found' and 'Result' columns in execution_table row 3.

At which step does nginx stop checking further index files?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at when 'File Found' changes to Yes in variable_tracker and execution_table.

If index.html existed, how would the execution_table change?

A Nginx would serve index.php anyway.

B Nginx would still check all files before serving.

C Nginx would serve index.html at step 1 and stop checking.

D Nginx would return an error.

💡 Hint

Index directive order means nginx serves the first found file, see concept_flow.

Concept Snapshot

Index directive syntax:
index file1 file2 file3;
When a directory URL is requested,
nginx checks these files in order.
It serves the first existing file found.
If none found, shows listing or error.

Full Transcript

The index directive in nginx specifies a list of files to look for when a client requests a directory URL. Nginx checks each file in the order listed until it finds one that exists. Then it serves that file. If no files are found, nginx may show a directory listing or an error. In the example, nginx checks index.html, then index.htm, then index.php. It finds index.php and serves it, stopping further checks. This process ensures the correct default file is served for directory requests.