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1130b656e5
This will make a number of things easier in the future, as well as (finally!) avoiding the Id-smashing problem which has plagued developers for so long. Boy, I'm glad we're not using sup anymore. This update would have been insane otherwise.
206 lines
5.4 KiB
Groff
206 lines
5.4 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" From: @(#)getgrent.3 8.2 (Berkeley) 4/19/94
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.\" $FreeBSD$
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.\"
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.Dd September 29, 1994
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.Dt GETGRENT 3
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.Os
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.Sh NAME
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.Nm getgrent ,
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.Nm getgrnam ,
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.Nm getgrgid ,
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.Nm setgroupent ,
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.\" .Nm setgrfile ,
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.Nm setgrent ,
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.Nm endgrent
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.Nd group database operations
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <grp.h>
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.Ft struct group *
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.Fn getgrent void
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.Ft struct group *
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.Fn getgrnam "const char *name"
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.Ft struct group *
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.Fn getgrgid "gid_t gid"
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.Ft int
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.Fn setgroupent "int stayopen"
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.\" .Ft void
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.\" .Fn setgrfile "const char *name"
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.Ft int
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.Fn setgrent void
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.Ft void
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.Fn endgrent void
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.Sh DESCRIPTION
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These functions operate on the group database file
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.Pa /etc/group
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which is described
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in
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.Xr group 5 .
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Each line of the database is defined by the structure
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.Ar group
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found in the include
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file
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.Aq Pa grp.h :
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.Bd -literal -offset indent
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struct group {
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char *gr_name; /* group name */
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char *gr_passwd; /* group password */
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gid_t gr_gid; /* group id */
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char **gr_mem; /* null terminated list of group members */
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};
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.Ed
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.Pp
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The functions
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.Fn getgrnam
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and
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.Fn getgrgid
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search the group database for the given group name pointed to by
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.Ar name
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or the group id pointed to by
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.Ar gid ,
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respectively, returning the first one encountered. Identical group
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names or group gids may result in undefined behavior.
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.Pp
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The
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.Fn getgrent
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function
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sequentially reads the group database and is intended for programs
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that wish to step through the complete list of groups.
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.Pp
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All three routines will open the group file for reading, if necessary.
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.Pp
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The
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.Fn setgroupent
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function
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opens the file, or rewinds it if it is already open. If
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.Fa stayopen
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is non-zero, file descriptors are left open, significantly speeding
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functions subsequent calls. This functionality is unnecessary for
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.Fn getgrent
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as it doesn't close its file descriptors by default. It should also
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be noted that it is dangerous for long-running programs to use this
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functionality as the group file may be updated.
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.Pp
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The
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.Fn setgrent
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function
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is identical to
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.Fn setgroupent
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with an argument of zero.
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.Pp
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The
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.Fn endgrent
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function
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closes any open files.
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.Sh YP/NIS INTERACTION
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When the
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.Xr yp 4
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group database is enabled, the
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.Fn getgrnam
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and
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.Fn getgrgid
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functions use the YP maps
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.Dq Li group.byname
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and
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.Dq Li group.bygid ,
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respectively, if the requested group is not found in the local
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.Pa /etc/group
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file. The
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.Fn getgrent
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function will step through the YP map
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.Dq Li group.byname
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if the entire map is enabled as described in
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.Xr group 5 .
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.Sh RETURN VALUES
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The functions
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.Fn getgrent ,
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.Fn getgrnam ,
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and
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.Fn getgrgid ,
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return a pointer to the group entry if successful; if end-of-file
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is reached or an error occurs a null pointer is returned.
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The functions
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.Fn setgroupent
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and
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.Fn setgrent
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return the value 1 if successful, otherwise the value
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0 is returned.
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The functions
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.Fn endgrent
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and
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.Fn setgrfile
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have no return value.
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.Sh FILES
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.Bl -tag -width /etc/group -compact
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.It Pa /etc/group
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group database file
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.El
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.Sh SEE ALSO
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.Fn getpwent 3 ,
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.Fn group 5 ,
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.Fn yp 4
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.Sh HISTORY
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The functions
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.Fn endgrent ,
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.Fn getgrent ,
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.Fn getgrnam ,
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.Fn getgrgid ,
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and
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.Fn setgrent
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appeared in
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.At v7 .
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The functions
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.Fn setgrfile
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and
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.Fn setgroupent
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appeared in
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.Bx 4.3 Reno .
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.Sh COMPATIBILITY
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The historic function
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.Fn setgrfile ,
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which allowed the specification of alternate password databases, has
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been deprecated and is no longer available.
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.Sh BUGS
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The functions
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.Fn getgrent ,
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.Fn getgrnam ,
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.Fn getgrgid ,
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.Fn setgroupent
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and
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.Fn setgrent
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leave their results in an internal static object and return
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a pointer to that object. Subsequent calls to
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the same function
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will modify the same object.
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