Help needed!

if I want to check if a file is on a server I use the following: ($file is specified in the url) if(file_exists("$file")) { echo " bla bla bla" } but when there is a file on the server called "File" and the file he´s looking for is "file" he doesn´t find it, so his seach is case sensetive. My question is now: Is it possible to make this search in- case sensitive?? Thanks