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revnetgroup(8) [freebsd man page]

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

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.byhost 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.byuser 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 databases. 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 <> BSD
October 24, 1995 BSD

Check Out this Related Man Page

netgroup(5yp)															     netgroup(5yp)

       netgroup - list of network groups

       The  file  defines network-wide groups used for permission checking when doing remote mounts, remote logins, and remote shells.	For remote
       mounts, the information in the file is used to classify machines; for remote logins and remote shells, it is used to classify users.   Each
       line of the file defines a group and has the following format:

       groupname member1,...,member_n

       Each member is either another group name or a combination of the host name, user name, and domain name.

       Any  of	the three fields can be empty, in which case a wildcard is assumed.  For example, to define a group to which everyone belongs, the
       following entry could appear in the file:
       universal (,,)

       Field names that begin with something other than a letter, digit, or underscore (such as ``-'') work in the opposite way.  For example:
       justmachines   (analytica,-,suez)
       justpeople     (-,babbage,suez)

       The machine analytica belongs to the group justmachines in the domain suez, but no users belong to it.  Similarly, the user babbage belongs
       to the group justpeople in the domain suez, but no machines belong to it.

       Network groups are part of the Yellow Pages data base and are accessed through these files:


       These files can be created from using


See Also
       getnetgrent(3yp), makedbm(8yp), ypserv(8yp)

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