can't write file on php

I am trying to create a file in the /tmp directory and unable to. It won't even let me create a file in the same dir I am in (/var/www/html). I believe I dont have the correct setting on my php.ini, but I dont know what I need to change to make this work. My OS is CentOS7 and I am running Apache with php 5.4.16. I do have read/write on /var/www/html and the user/group is set to apache. Below is just a generic code to write a file which is not working, I keep getting "Unable to open file" $myfile = fopen("newfile.txt", "w") or die("Unable to open file!"); $txt = "John Doe\n"; fwrite($myfile, $txt); fclose($myfile);