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Re: Q
On Thu, 29 Jan 1998, Erez Doron wrote:
> Hi
>
> does anybody knows of a unix command that
> checks if a there is such a user on the system ?
>
> i meen that I'll ask if there is a username 'yossi' or 'moshe'
> on this host, and I'll get an answer
>
> ( do not tell me 'finger', this requires a daemon )
It depends whether you want to do local lookups or remote.
Remote:
You cannot find out if a user is on the remote system without it having
some daemon running, like sendmail for example. If the remote system is
part of a NIS domain, and the host you are on can hear broadcasts from the
network the NIS master server or slave servers sits on, then you can do:
ypbind -ypset
ypset the.master/slaver.nis.server
Then, do ypmatch username passwd. This is not full proof though, since
through netgroups one can restrict access on a computer to a certain
netgroup. You can see a user's netgroups by issuing:
ypmatch username.\* netgroup.byuser
for example. (assuming that the site is using netgroup.byname and
netgroup.byuid NIS maps for the netgroups, which is the default I think).
You mileage may vary.
Local:
There are quite a few ways to find a local user, starting with the "id
username", through using shell/awk one liners, Perl, Tcl, C, C++ :)) etc
etc etc. All these solutions will be accessing /etc/passwd and look fo a
string you ask them for.
For NIS, you can also use ypmatch username passwd. and as I said in the
Remote paragraph, you need to check if there aren't any netgroup
restrictions, but the difference here is that you can find out for sure if
a NIS user can or cannot access the machine, since you can look it
/etc/passwd and see what netgroups are allowed access, and compare it with
the list of available netgroups for the user.
Regards,
--Ariel
>
> regards
> Erez.
>
>
>
+---------------------------------------------------------------+
| Ariel Biener |
| e-mail: ariel@post.tau.ac.il Work ph: 03-6406086 |
| fingerprint = 07 D1 E5 3E EF 6D E5 82 0B E9 21 D4 3C 7D 8B BC |
+---------------------------------------------------------------+
- References:
- Q
- From: Erez Doron <erez@savan.com>