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

NAME
     revnetgroup -- generate reverse netgroup data

SYNOPSIS
     revnetgroup -u -h [-f netgroup_file]

DESCRIPTION
     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. Seperate databases are created to hold information pertaining to users and
     hosts; this allows netgroup username lookups and netgroup hostname lookups to be performed using inde-pendent independent
     pendent 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 consider-able considerable
     able 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.

OPTIONS
     The revnetgroup command supports the following options:

     -u    Generate netgroup.byuser output; only username information in the original netgroup file is pro-cessed. processed.
           cessed.

     -h    Generate netgroup.byhost output; only hostname information in the original netgroup file is pro-cessed. processed.
           cessed. (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.

FILES
     /var/yp/<domain>Makefile          The Makefile that calls makedbm and revnetgroup to build the YP data-bases. databases.
                                       bases.
     /etc/netgroup                     The default netgroup database file. This file is most often found
                                       only on the YP master server.

SEE ALSO
     getnetgrent(3), yp(8), netgroup(5), makedbm(8)

AUTHOR
     Bill Paul <wpaul@ctr.columbia.edu>

BSD                            October 24, 1995                            BSD