NAME    [Toc]    [Back]

     revnetgroup - generate reverse netgroup data

SYNOPSIS    [Toc]    [Back]

     revnetgroup -u -h [-f netgroup_file]

DESCRIPTION    [Toc]    [Back]

     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.  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
     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 considerable 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.

     The options are as follows:

     -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.

FILES    [Toc]    [Back]

     /var/yp/<domain>Makefile  The Makefile that calls makedbm(8)
and
                               revnetgroup  to   build   the   YP
databases.
     /etc/netgroup               The  default  netgroup  database
file.  This file
                               is most often found only on the YP
master server.

SEE ALSO    [Toc]    [Back]

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

AUTHORS    [Toc]    [Back]

     Bill Paul <[email protected]>

OpenBSD      3.6                         October     24,     1995