alternative /etc/passwd formats (was: Corrupted passwd file woes)

Cameron Simpson,Uhmmm..???? Who knows cameron at usage.csd.oz
Tue Sep 18 23:00:00 AEST 1990


I wrote:
| >Well, when I started Uni in '84 we had a couple of PDP11/70s and
| >a couple of VAXen running a heavily hacked V7 UNIX. /etc/passwd
| >was an autolocking binary file [...] Of course you
| >couldn't grep /etc/passwd for stuff,

>From article <4073 at auspex.auspex.com>, by guy at auspex.auspex.com (Guy Harris):
|  4.3BSD and later have a similar approach; the difference is that
|  "/etc/passwd" is *still* a text file, that you can *still* grep, but the
|  password file that "getpwnam()" and "getpwuid()" get entries from is an
|  "ndbm" database file.  "vipw" (a misnamed program, it doesn't shove "vi"
|  down your throat) will rebuild the "dbm" database if you change the
|  password file with it.

I don't think dbm existed then :-) This was (is) just a binary file
with indices for uid and login at the front, strings down the back
- we just compact it once a week.

| >We currently have about 180 Apollos with 3122 accounts listed.
| >The Apollos use a loosely coupled database for account information
| >and /etc/passwd is a special file supported by a subsystem which
| >generates a standard looking file when you open it for read.
|  
|  So did they modify "getpwnam()" and "getpwuid()" to talk directly to the
|  registry, or do they still grovel through said special file?

No, they talk directly to the server. And there's some local caching for
when things are bad (infrequent - there are four replicas on our network,
rarely are all four down).
	- Cameron Simpson



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