revnetgroup(8) BSD System Manager's Manual revnetgroup(8)
NAME
revnetgroup -- generate reverse netgroup data
SYNOPSIS
revnetgroup -u | -h [-f netgroup_file]
DESCRIPTION
The revnetgroup utility processes the contents of a file in netgroup(5)
format into what is called reverse netgroup form. That is, where the
original file shows netgroup memberships in terms of which members reside
in a particular group, the reverse netgroup format specifies what groups
are associated with a particular member. This information is used to
generate the netgroup.byuser and netgroup.byhosts NIS maps. These
reverse netgroup maps are used to help speed up netgroup lookups, partic-
ularly for the innetgr() library function.
For example, the standard /etc/netgroup file may list a netgroup and a
list of its members. Here, the netgroup is considered the key and the
member names are the data. By contrast, the reverse netgroup.byusers
database lists each unique member as the key and the netgroups to which
the members belong become the data. Separate databases are created to
hold information pertaining to users and hosts; this allows netgroup
username lookups and netgroup hostname lookups to be performed using
independent keyspaces.
By constructing these reverse netgroup databases (and the corresponding
NIS maps) in advance, the getnetgrent(3) library functions are spared
from having to work out the dependencies themselves on the fly. This is
important on networks with large numbers of users and hosts, since it can
take a considerable amount of time to process very large netgroup data-
bases.
The revnetgroup utility prints its results on the standard output. It is
usually called only by /var/yp/Makefile when rebuilding the NIS netgroup
maps.
OPTIONS
The revnetgroup utility supports the following options:
-u Generate netgroup.byuser output; only username information in the
original netgroup file is processed.
-h Generate netgroup.byhost output; only hostname information in the
original netgroup file is processed. (Note at least one of the
-u or -h flags must be specified.)
[-f netgroup_file]
The revnetgroup utility uses /etc/netgroup as its default input
file. The -f flag allows the user to specify an alternate input
file. Specifying ``-'' as the input file causes revnetgroup to
read from the standard input.
FILES
/var/yp/Makefile the Makefile that calls yp_mkdb and revnetgroup to
build the NIS databases
/etc/netgroup the default netgroup database file. This file is most
often found only on the NIS master server
SEE ALSO
getnetgrent(3), netgroup(5), yp(8), yp_mkdb(8)
AUTHORS
Bill Paul <wpaul@ctr.columbia.edu>
BSD October 24, 1995 BSD
Mac OS X 10.8 - Generated Tue Sep 4 09:03:31 CDT 2012