How to set a mime type on a file with php? -

How to set a mime type on a file with php? -

i writing unit test class , need generate few files different mime-types.

i know how set mime-type when sending file remote user (ala header()), how when using fwrite() on local server?

for file generated in method mime-type derived straight file extension?

i'm using php 5.3.x on ubuntu 12.04

files don't have mime types. identified file extensions. mime types set file extensions in /etc/mime.types. mime type tell client programme utilize open file.

php mime-types fwrite