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revnetgroup(8)

NAME

     revnetgroup -- generate reverse netgroup data

SYNOPSIS

     revnetgroup -u [-f netgroup_file]
     revnetgroup -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

FreeBSD 5.4		       October 24, 1995 		   FreeBSD 5.4

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