fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
287 lines
6.7 KiB
Groff
287 lines
6.7 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. 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 July 31, 2016
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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 getgrent_r ,
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.Nm getgrnam ,
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.Nm getgrnam_r ,
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.Nm getgrgid ,
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.Nm getgrgid_r ,
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.Nm setgroupent ,
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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 LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In grp.h
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.Ft struct group *
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.Fn getgrent void
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.Ft int
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.Fn getgrent_r "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result"
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.Ft struct group *
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.Fn getgrnam "const char *name"
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.Ft int
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.Fn getgrnam_r "const char *name" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result"
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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 getgrgid_r "gid_t gid" "struct group *grp" "char *buffer" "size_t bufsize" "struct group **result"
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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 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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.Vt group
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found in the include
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file
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.In 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; /* 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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.Fa name
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or the group id pointed to by
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.Fa gid ,
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respectively, returning the first one encountered.
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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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The functions
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.Fn getgrent_r ,
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.Fn getgrnam_r ,
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and
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.Fn getgrgid_r
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are thread-safe versions of
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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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respectively.
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The caller must provide storage for the results of the search in
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the
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.Fa grp ,
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.Fa buffer ,
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.Fa bufsize ,
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and
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.Fa result
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arguments.
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When these functions are successful, the
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.Fa grp
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argument will be filled-in, and a pointer to that argument will be
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stored in
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.Fa result .
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If an entry is not found or an error occurs,
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.Fa result
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will be set to
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.Dv NULL .
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.Pp
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These functions 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.
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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.
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This functionality is unnecessary for
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.Fn getgrent
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as it does not close its file descriptors by default.
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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 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 a group structure on success or
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.Dv NULL
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if the entry is not found or if an error occurs.
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If an error does occur,
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.Va errno
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will be set.
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Note that programs must explicitly set
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.Va errno
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to zero before calling any of these functions if they need to
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distinguish between a non-existent entry and an error.
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The functions
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.Fn getgrent_r ,
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.Fn getgrnam_r ,
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and
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.Fn getgrgid_r
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return 0 if no error occurred, or an error number to indicate failure.
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It is not an error if a matching entry is not found.
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(Thus, if
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.Fa result
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is set to
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.Dv NULL
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and the return value is 0, no matching entry exists.)
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.Pp
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The function
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.Fn setgroupent
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returns 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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.Fn setgrent
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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 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 SEE ALSO
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.Xr getpwent 3 ,
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.Xr group 5 ,
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.Xr nsswitch.conf 5 ,
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.Xr yp 8
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.Sh STANDARDS
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The
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.Fn getgrent ,
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.Fn getgrnam ,
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.Fn getgrnam_r ,
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.Fn getgrgid ,
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.Fn getgrgid_r
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and
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.Fn endgrent
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functions conform to
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.St -p1003.1-96 .
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The
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.Fn setgrent
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function differs from that standard in that its return type is
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.Vt int
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rather than
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.Vt void .
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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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The functions
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.Fn getgrent_r ,
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.Fn getgrnam_r ,
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and
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.Fn getgrgid_r
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appeared in
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.Fx 5.1 .
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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.
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Subsequent calls to
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the same function
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will modify the same object.
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.Pp
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The functions
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.Fn getgrent ,
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.Fn getgrent_r ,
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.Fn endgrent ,
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.Fn setgroupent ,
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and
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.Fn setgrent
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are fairly useless in a networked environment and should be
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avoided, if possible.
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The
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.Fn getgrent
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and
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.Fn getgrent_r
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functions
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make no attempt to suppress duplicate information if multiple
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sources are specified in
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.Xr nsswitch.conf 5 .
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