RewriteEngine On


RewriteBase /svgs/avatars/

Options +FollowSymlinks


#RewriteCond %{REQUEST_FILENAME} !-d
#RewriteCond %{REQUEST_FILENAME} !-f

#RewriteRule . 0.svg [L]

RewriteCond %{THE_REQUEST} !avatars/0.svg  
RewriteRule ^(.*)$ 0.svg [R=307,L]