Migrating from WAMP to LAMP: File write errors from PHP
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I'm porting a web system from Windows to Linux. I've solved most of the small issues, but this one is getting to me. I've got a text file which PHP writes logging information to. At the moment, PHP fails to open the file, citing 'permission denied'. As far as I'm aware:

 - The directory and the file to be written have 770 permissions
 - The directory and all the files below it are owned by the user 'web', and the group 'web'
 - Apache is being run by user 'web'*

*I checked this by running:

    ps aux | grep apache

Any ideas? I can't figure this one out. I tested setting the directory and the file to 777 permissions, and I was able to write to file - obviously this isn't a viable workaround, this file is internal to the system and shouldn't be accessible externally.