a very common try_files line which can be applied on your condition is
location / {
try_files $uri $uri/ /test/index.html;
}
you probably understand the first part, location / matches all locations, unless it's matched by a more specific location, like location /test for example
The second part ( the try_files ) means when you receive a URI that's matched by this block try $uri first, for example http://example.com/images/image.jpg nginx will try to check if there's a file inside /images called image.jpg if found it will serve it first.
Second condition is $uri/ which means if you didn't find the first condition $uri try the URI as a directory, for example http://example.com/images/, ngixn will first check if a file called images exists then it wont find it, then goes to second check $uri/ and see if there's a directory called images exists then it will try serving it.
Side note: if you don't have autoindex on you'll probably get a 403 forbidden error, because directory listing is forbidden by default.
EDIT: I forgot to mention that if you have
indexdefined, nginx will try to check if the index exists inside this folder before trying directory listing.
Third condition /test/index.html is considered a fall back option, (you need to use at least 2 options, one and a fall back), you can use as much as you can (never read of a constriction before), nginx will look for the file index.html inside the folder test and serve it if it exists.
If the third condition fails too, then nginx will serve the 404 error page.
Also there's something called named locations, like this
location @error {
}
You can call it with try_files like this
try_files $uri $uri/ @error;
TIP: If you only have 1 condition you want to serve, like for example inside folder images you only want to either serve the image or go to 404 error, you can write a line like this
location /images {
try_files $uri =404;
}
which means either serve the file or serve a 404 error, you can't use only $uri by it self without =404 because you need to have a fallback option.
You can also choose which ever error code you want, like for example:
location /images {
try_files $uri =403;
}
This will show a forbidden error if the image doesn't exist, or if you use 500 it will show server error, etc ..