I have a web root containing a wordpress installation. When a some_user uploads new source code and over-writes files (e.g., .htaccess or index.php) or creates new files, I need for the ownership of the files to be apache:some_user.

I understand that umask determines the permissions of newly created files. Is there some command that determines ownership of newly created files?

You can use the setgid bit on the top level directory to enforce group ownership of files, but actual owner is not affected. If the method for updating files on the site was to upload via ftp then you can force the ownership, vsftpd can do this with the chown_uploads and chown_username directives, other ftp servers may have similar options.

Could you be more specific? I'm not familiar with setgid, but it sounds like you are saying this only affects group ownership of new files and not their user ownership. Please clarify.

I don't have any FTP server installed. Access to the server is accomplished via certificated-authenticated SFTP. I assume the mechanism of file transfer is SCP.

setuid (aka suid) and sgid
https://en.wikipedia.org/wiki/Setuid
http://kmaiti.blogspot.com.au/2011/0...ticky-bit.html

The ssh pkg includes 3 tools
a) ssh - encrypted terminal access
b) scp - encrypted cp
c) sftp - encrypted ftp
http://www.openssh.com/manual.html

HTH

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Thanks for the links. From the Wikipedia, this disappointing tidbit:
which suggests that I'm out of luck.

I might, on the other hand try and alter some configuration of ssh or scp or sftp such that I can apply a setuid setting to *one specific user* but I've got no idea where to do that -- or if it's even possible.

I see from this url that sftp supports chown (I figured as much) but I have never had any luck at all changing the owner of a file without root permissions -- even if I own the file.

Although you can't force newly created files to have some specifc owner, but using setgid you can force newly created files/directories to inherit group of parant directory.
On the other hand, set sticky bit permission on parant directory to protect it from unauthorized modifications, as:-
It will then allow only root, owner of parant dir. or onwer of file/sub-directory to modify contents.

Don't forget that sshd is owned by root, so sftp can change owners for you, if that's what you really want.
Generally webpages are owned by the apache (acct name might be www or some such) user; wordpress is probably the same/similar.

1 members found this post helpful.

Chris, it had not occurred to me that sshd is owned by root but that makes complete sense. The question is then "how do I alter my sshd config such that all files uploaded by user foo to directory /var/www/html are owned by apache:foo" ? I've checked 'man sshd_config' and find no mention of setuid in there. I tend to doubt such a specific configuration option is available.

In case anyone is wondering, the reason I ask is due to the way that Wordpress checks file ownership. It attempts to create a temporary file in the webroot somewhere and then checks the owner of that file. If the owner is not apache, then it resorts to prompting the user for FTP/SFTP credentials. Not the end of the world, but an unnecessary extra step IMHO.

Forget setuid, that's a completely different concept.
Here you just need to set the actual owner, which sftp supports as you've noticed.