couple of getpwnam() questions

Steve Langasek vorlon at
Sat Nov 25 16:43:14 GMT 2000

On Sun, 26 Nov 2000 okuyamak at wrote:

> I don't really know what is the "right" cases about
> 'Administorator's. But if I were....

> >>>>> "GC" == Gerald Carter <gcarter at> writes:
> GC> No one responded to this.  Should I threaten making 
> GC> the change to issue #1 unless I hear differently?
> GC> Does anyone depend on this behavior currently?

> I don't even see the reason why current code uses this way.
> Instead, I recommend using getpwent() function, take out each entry,
> and do case insensitive match, or what ever match required.

> # or, simply open the /etc/passwd file directly and look for
> # entry.


> At least, getpwnam() will open(), close() and scan entire
> /etc/passwd every time being called. This is large overhead, too
> large. With 'getpwent() + case insensitive match', we only need
> to scan once, though we might need more complex matching engine.

This is true when getpwnam() uses a flatfile (/etc/passwd) for its backend,
but this is not always the case, and therefore getpwent() is not always going
to be much more efficient.  With some database backends (NIS+, LDAP, Berkeley
DB, for example), you may find that calling getpwnam("user") is a *LOT* more
efficient than iterating through getpwent().

I think Gerald's question is still relevant: even if there is a more efficient
way to do what the code currently does, *why* is it being done at all?

Steve Langasek
postmodern programmer

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