How to make php webpage to access the file in /root directory?

Question

I am using Linux 12.04,apache and php is installed on it.I want to access a text file in /root/ folder.I am really confused with the permissions.The php script i m using

<?php
$file = fopen("/root/cr.txt", "r") or exit("Unable to open file!");
//Output a line of the file until the end is reached

while(!feof($file))
  {
  echo fgets($file). "<br>";
  }

fclose($file);
?> 

This script is able to access the file /var/www folder but not able to access /root/ip.txt file. Please help and explain step to step possible.

Solution

I will forget about the security implications of doing this and will go down to business:

If you have done ls -l /var/www and ls -l /root you would have noticed that both has different permissions:

$ ls -l /root/cr.txt
total 2
-rw-r-----  1 root root    0 Jul  9 01:28 cr.txt
$ ls -l /var/www
total 2
-rw-r--r--  1 www-data www-data    0 Jul  9 01:28 somefile

The /root is only readable for root, while /var/www is readable by www-data user. Now, if you check apache process you will notice that it's running using the www-data user.

$ ps aux | grep apache www-data 5133 0.0 0.2 6512 1208 ? R+ 10:04 0:00 apache

Now, you are trying to make apache running with the www-data user read the file. You can take three courses of action:

1. Move the file to /var/www and change it's permissions so www-data users can read it.

   mv /root/cr.txt /var/www/
   chown www-data:www-data /var/www/cr.txt
   

   This is the preferable method.

2. Create a symlink to the file in the /var/www directory:

   ln -s /root/cr.txt /var/www/
   

   This won't ensure that your file is being read, in some cases.

3. This is dangerous and should not be done! Add the www-data user to the root group, or change the file ownership so it could be read by www-data users:

   chown :www-data /root/cr.txt
   ## Or
   sudo adduser www-data root
   

   This shouldn't be done if you don't understand the risks!

Comments

[karlingen]

Double-check your code. You are saying /root/ip.txt in the comment but in the code you are writing /root/cr.txt

[Braiam]

Edit your post and include the output of ls -l /root/cr.txt

[acekapila]

i have added the www-data to root ,but still it's not working.The script is not able to get content of /root/cr.txt