Unable to write files on CentOS

Question

I have a VPS running on CentOS 6 and apache2 as webserver. I have several PHP scripts running in my server, and everything goes smooth, except to file writing. For some reason, my PHP scripts are unable to write or create files.

I am using the default location /var/www/html/ which is owned by root:root.

I have tried temporarily CHMODing directories and files, without success.
I also tried setting the folder permissions to 777, same result - no success.

This is quite strange, and I'm a beginner when it comes to managing VPSes.

I added the PHP error log line to php.ini and told it to store the log in /var/log/

Solution

CentOS is one of those operating systems which often comes with some form of SELinux installed. There are several holy wars as to whether using SELinux is a good thing or a waste, but it is a choice you will have to make.

If you are still a beginner I would recommend that you spend time with SELinux turned off, and then once you have everything running you can optionally enable it and start reconfiguring.

NB: The real world way of doing things is the opposite: start with a completely locked down system and one by one enable things that you need.

Comments

[ganesh]

1) Under which user ID to the PHP scripts run? 2) To which directories are you trying to write? 3) Chmod 777 is a really bad idea. Please undo. 4) Any errors in the logs?

[aborted]

1) I don't know, how do I find out? 2) /var/www/html 3) It was just a try, I undid it immediately 4) No, if the logs are in /var/log/ then there is no error log at all.

[aborted]

1) I'm using apache2, sorry for not mentioning that. 2) It appears that root is the owner of /var/www/html (I used la -l, to check that, two columns keep saying "root"). 3) I added the PHP error log line myself on php.ini, and I told it to store the log in /var/log/

[ganesh]

Do you have an apache2.conf? Does it have these two lines and what is the exact content of those lines? User ${APACHE_RUN_USER} Group ${APACHE_RUN_GROUP}

[aborted]

If apache2.conf is the same as httpd.conf, then I do have it. If you're asking exactly for apache2.conf, I honestly don't know if I have it. My httpd.conf doesn't have those two lines.

[Lawrence]

What errors come up when you try to use php to write a file ?

[aborted]

@Lawrence, none at all, it just doesn't work -- nothing happens.

[LuckySpoon]

@Dugi I think @Hennes meant that there'll be a line that starts User followed by a user name, and a line that starts Group that's followed by a group name. E.g. User apache Group apache - chown -R the directory to that user/group combo - e.g. chown -R apache:apache /var/www/html Edit: Also 777 should only be used where needed - 644 should get you through most places, and just 777 what needs to be written to, and even then only if 644 and 755 doesn't do it.

[ganesh]

I meant it slightly more detailed. And 777 (WORLD WRITABLE!) is not a good idea. It is even such a bad idea that you may find web servers actually blocking the directory containing the HTML files because it is unsafe. But other than that, yes, that is where I was trying to guide him to.

[aborted]

I'm running an image hosting website, and I need to store all images inside a folder. I also tend to store logs in .log text files instead of the database, and I can't seem to be able to append text to the files.

[harrymc]

Use PHP as above to create a directory and a file in it, then examine its owner and permissions. That will give you all the info you need.

[Dave Hollingworth]

Thank you so much for this - I've had to migrate a Debian server to CentOS and for the life of me I couldn't work out why the exact same configuration wouldn't work (I was getting file permission errors with PHP all over the place), until I turned SELinux off... if it's useful for anyone reading this I followed the instructions here to switch it off