Can't write to /tmp with php, despite 777 permissions and no open_basedir value

Question

I\'m trying to write a file to my /tmp directory (on an apache server) with the php fopen function, but it fails:

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Answer 1

Your problem is likely caused by the combination of systemd and apache. It's a security feature called PrivateTmp, and obviously it's an opt out.

If you don't want it, you can disable it like this:

1. Outcomment the respective switch in /etc/systemd/system/multi-user.target.wants/apache2.service: #PrivateTmp=true
2. Restart systemd: sudo systemctl daemon-reload
3. Restart apache: sudo systemctl restart apache2