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38 .Nd "generate reverse netgroup data"
42 .Op Fl f Ar netgroup_file
46 utility processes the contents of a file in
48 format into what is called
51 That is, where the original file shows
52 netgroup memberships in terms of which members reside in a particular
53 group, the reverse netgroup format specifies what groups are associated
54 with a particular member.
55 This information is used to generate the
61 These reverse netgroup maps are used to help speed up
62 netgroup lookups, particularly for the
66 For example, the standard
68 file may list a netgroup and a list of its members.
70 netgroup is considered the
72 and the member names are the
74 By contrast, the reverse
76 database lists each unique
77 member as the key and the netgroups to which the members belong become
79 Separate databases are created to hold information pertaining
80 to users and hosts; this allows netgroup username lookups
81 and netgroup hostname lookups to be performed using independent keyspaces.
83 By constructing these reverse netgroup databases (and the corresponding
87 library functions are spared from having to work out the dependencies
88 themselves on the fly.
89 This is important on networks with large numbers
90 of users and hosts, since it can take a considerable amount of time
91 to process very large netgroup databases.
95 utility prints its results on the standard output.
105 utility supports the following options:
106 .Bl -tag -width indent
110 output; only username information in the
111 original netgroup file is processed.
115 output; only hostname information in the
116 original netgroup file is processed.
117 (Note at least one of the
121 flags must be specified.)
122 .It Op Fl f Ar netgroup_file
127 as its default input file.
130 flag allows the user to specify an alternate input file.
132 as the input file causes
134 to read from the standard input.
137 .Bl -tag -width /var/yp/Makefile -compact
138 .It Pa /var/yp/Makefile
139 the Makefile that calls
147 the default netgroup database file.
148 This file is most often found
159 .An Bill Paul Aq Mt wpaul@ctr.columbia.edu