htaccess Redirect when 404

Question

I have a subdirectory called /marker, in it are some png files. Now I want the file /marker/standard.png to be returned whenever an attempt is made to call a png that does not exist. In other words: If, for example, /marker/doesntexist.png is called (which doesn't exist), /marker/standard.png should be delivered.

Sounds quite simple, but several attempts with RewriteRule or ErrorDocument failed.

Any ideas? tia

Answer 1

You can do the following to serve /marker/standard.png if another .png file in the /marker directory is requested that does not exist.

This uses mod_rewrite and should go near the top of the .htaccess file in the document root.

RewriteEngine On

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^marker/(?!standard\.png$).+\.png$ marker/standard.png [L]

I took the extra step to exclude requests for standard.png itself (using a negative lookahead), in case this doesn't exist for some reason.

Note that this is a case-sensitive string comparison. eg. Only .png files are matched, not .PNG.

This naturally results in a 200 OK response when standard.png is served. If you still need a 404 Not Found status then use ErrorDocument instead (see the next section).

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Using ErrorDocument

You also mentioned the use of an ErrorDocument directive. This is another solution, although it will result in a 404 HTTP response status, which may or may not be desirable.

For example, in order to restrict this ErrorDocument just to the /marker subdirectory then create an additional .htaccess file in this subdirectory with the following:

ErrorDocument 404 /marker/standard.png

This will naturally serve standard.png for any non-existent request to the /marker subdirectory. To restrict this to .png requests only then wrap the ErrorDocument in an <If> expression. For example:

<If "%{REQUEST_URI} =~ /\.png$/">
    ErrorDocument 404 /marker/standard.png
</If>