[Nss-mysql-users] General nss-mysql questions...

[Michael Chang]

Hi, folks.

I recently downloaded and installed nss-mysql, and, so far, while it 
appears to work as advertised, I'm wondering about a few things (note: I
compiled it with debugging turned on):


1.) 
  While tailing my logfiles, a looked carefully at the results during
  a call to `finger <username>'.  Let's call the results 'x', for now.
  After the call to finger, I called `chfn <username>'.  Let's call 
  the logfile results while calling chfn 'y'.
  Now, I noticed that 'x' and 'y' are equal; additionally, no rows
  in the database were updated, and chfn only ended up updating
  the information in /etc/passwd instead of in the database.
  So, it appears as though nss-mysql can *retrieve* from a MySQL
  database, but updates are still performed on the flat files
  under /etc.
  Is this really the way that nss-mysql is intended to operate?


2.)
  Where does nss-mysql sit in the grand scheme of things?  I'm guessing
  that when getpwent(), getgrnam(), etc., are called, libnss is loaded
  and, in turn, libnss_<service>.so is loaded.  Thence, the nss service
  module loaded by libss is responsible for doing all the work.  If
  my assumption is correct, I imagine that this behaviour is hardcoded
  in glibc somewhere in order to provide a consistent and global manner
  of doing lookups, otherwise you could get ugly race conditions and
  data corruption if there was more than one scheme used to get info
  from the different databases found in /etc/nsswitch.conf.
  Please correct me if I'm wrong anywhere.
  If I am correct, then I guess that even PAM itself uses NSS to
  perform lookups.



Thanks,
Michael






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