Section 3 : Running a Server

Q317: Why have fax user?

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Why have fax user?

I've been trying to figure out why there is a need for a "fax" user. I'm running AIX 3.2.5 (and I checked this under Solaris as well). It seems that if the fax user has the same userid as uucp, then for any sort of lookup, uucp will be returned when one might want fax's userid.

For example, I have a file. I do a 'chmod fax filename' and then do an ls -l. ls shows that the file is now owned by uucp. In addition, if I try to use faxrm from the fax userid to remove someone elses job, faxrm reports that I'm not the fax user. So, in the end, I can not remove anyone's fax job if I am not the fax user, which I will never be because faxid = 5 = uucpid.

So, why the fax user? Why not run everything under uucp? If there are compelling reasons, where is the code which faxrm uses to check if you are the owner of a fax or the "fax" user? (I looked and looked, but nothing seemed obvious)

Because the "fax" user has a separate passwd file entry it can have a private passwd different from uucp. The reason that it's got the same uid as uucp is to simplify management of the UUCP lock files and tty device protections. It should be possible to have a uid different from uucp (at one time it did), but right now the code has some assumptions that require it to be identical. At some point in the future the requirement that the fax&uucp uids be the same may be eliminated (patches welcome).

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