Updated: 2021/Apr/14

REVNETGROUP(8)              System Manager's Manual             REVNETGROUP(8)

     revnetgroup - generate reverse netgroup data

     revnetgroup [-hu] [-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 NIS 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
     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

     The revnetgroup command prints its results on the standard output. It is
     usually called only by /var/yp/<domain>/Makefile when rebuilding the NIS
     netgroup maps.

     The revnetgroup command 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 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.

     /var/yp/<domain>/Makefile         The Makefile that calls makedbm 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.

     getnetgrent(3), netgroup(5), makedbm(8), nis(8)

     Bill Paul <wpaul@ctr.columbia.edu>

NetBSD 9.99                    February 26, 2005                   NetBSD 9.99