REVNETGROUP(8) | System Manager's Manual | REVNETGROUP(8) |
revnetgroup
—
generate reverse netgroup data
revnetgroup |
-h | -u
[-f netgroup_file] |
revnetgroup
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 YP maps. These reverse netgroup
maps are used to help speed up netgroup lookups, particularly 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 YP 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 databases.
The revnetgroup
command prints its results
on the standard output. It is usually called only by
/var/yp/<domain>/Makefile when rebuilding the
YP netgroup maps.
The options are as follows:
-f
netgroup_filerevnetgroup
command 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.-h
-u
revnetgroup
to build the YP databases.Bill Paul <wpaul@ctr.columbia.edu>
August 14, 2013 | OpenBSD-5.8 |