How to give PHP write permission to a directory?

Question

I'm trying to create a file using PHP but it's not working. I'm assuming this is because it doesn't have write access (has been this problem before). I tried to test if this was the problem by chmod 0777 the folder, but this ended up causing every script in that directory to return a 500 error message until I changed it back. How do I give PHP write access to my file system so it can create files?

EDIT: It is hosted on Hostgator shared hosting using Apache.

Edit 2: Someone asked about the code: The code is a GD image script. I know the rest of it works just like before when I created the image every time I called it. Now I try to create them when adding new text and save them to a folder. My write line is: imagejpeg(null,$file,85);

I also created a test file to check if it was just a broken script (mostly copied from tizag): http://gearboxshow.info/rkr/lesig.jpg/testfile.txt (I don't know if/how to post the code here correctly. This is the content of the PHP script, minus the PHP tags.)

It returns 13,13,1 (separate lines), so it looks like it thinks it wrote something, but testfile.txt is blank (I uploaded a blank one), or doesn't exist (if I delete it)).

Edit 3: The server is running CentOS.

Answer 1

Simple three-step solution

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Step 1: Identify PHP User

Create a PHP file with the following content:

<?php echo `whoami`; ?>

Upload it to your web server. The output should resemble the following:

www-data

Therefore, the PHP user is www-data.

---

Step 2: Determine the directory owner

Next, check the details of the web directory via the command line:

ls -dl /var/www/example.com/public_html/example-folder

The result should look similar to the following:

drwxrwxr-x 2 exampleuser1 exampleuser2 4096 Mar 29 16:34 example-folder

Therefore, the owner of this directory is exampleuser1.

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Step 3: Change directory owner to PHP user

Then, change the owner of the web directory to the PHP user:

sudo chown -R www-data /var/www/example.com/public_html/example-folder

Verify that the owner of the web directory has changed:

ls -dl /var/www/example.com/public_html/example-folder

The result should look similar to the following:

drwxrwxr-x 2 www-data exampleuser2 4096 Mar 29 16:34 example-folder

At this point, the owner of example-folder has been successfully changed to the PHP user: www-data.

---

Finish! PHP should now be able to write to the directory.

Answer 2

A simple way is to have PHP create the directory itself first.

<?php
 $dir = 'myDir';

 // create new directory with 744 permissions if it does not exist yet
 // owner will be the user/group the PHP script is run under
 if ( !file_exists($dir) ) {
     mkdir ($dir, 0744);
 }

 file_put_contents ($dir.'/test.txt', 'Hello File');

This can save you trouble with permissions.