f14fb60209
* Updating common/lib * Updating lib/csu * Updating lib/libc * Updating libexec/ld.elf_so * Corrected test on __minix in featuretest to actually follow the meaning of the comment. * Cleaned up _REENTRANT-related defintions. * Disabled -D_REENTRANT for libfetch * Removing some unneeded __NBSD_LIBC defines and tests Change-Id: Ic1394baef74d11b9f86b312f5ff4bbc3cbf72ce2
345 lines
7.6 KiB
Groff
345 lines
7.6 KiB
Groff
.\" $NetBSD: getgrent.3,v 1.31 2011/04/28 16:34:01 wiz Exp $
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.\"
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.\" 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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.\" @(#)getgrent.3 8.2 (Berkeley) 4/19/94
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.\"
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.Dd April 30, 2008
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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 getgrgid ,
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.Nm getgrgid_r ,
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.Nm getgrnam ,
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.Nm getgrnam_r ,
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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 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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.Fo getgrent_r
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.Fa "struct group *grp"
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.Fa "char *buffer"
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.Fa "size_t buflen"
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.Fa "struct group **result"
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.Fc
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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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.Fo getgrgid_r
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.Fa "gid_t gid"
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.Fa "struct group *grp"
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.Fa "char *buffer"
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.Fa "size_t buflen"
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.Fa "struct group **result"
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.Fc
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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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.Fo getgrnam_r
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.Fa "const char *name"
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.Fa "struct group *grp"
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.Fa "char *buffer"
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.Fa "size_t buflen"
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.Fa "struct group **result"
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.Fc
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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 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 which is described 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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.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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.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.
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Identical group names or group ids 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 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 functions will open the group file for reading, if necessary.
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.Pp
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The functions
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.Fn getgrnam_r ,
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.Fn getgrgid_r ,
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and
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.Fn getgrent_r
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act like their non re-entrant counterparts
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respectively, updating the contents of
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.Ar grp
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and storing a pointer to that in
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.Ar result ,
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and returning
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.Dv 0 .
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Storage used by
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.Ar grp
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is allocated from
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.Ar buffer ,
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which is
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.Ar buflen
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bytes in size.
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If the requested entry cannot be found,
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.Ar result
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will point to
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.Dv NULL
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and
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.Dv 0
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will be returned.
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If an error occurs,
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a non-zero error number will be returned and
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.Ar result
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will point to
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.Dv NULL .
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Calling
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.Fn getgrent_r
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from multiple threads will result in each thread reading a disjoint portion
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of the group database.
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.Pp
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The
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.Fn setgroupent
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function 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 doesn't close its file descriptors by default.
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It should also be noted that it is dangerous for long-running
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programs to use this 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 is equivalent 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 closes any open files.
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.Sh RETURN VALUES
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The functions
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.Fn getgrgid ,
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.Fn getgrnam ,
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and
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.Fn getgrent
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return a valid pointer to a group structure on success
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and a
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.Dv NULL
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pointer if the entry was not found or an error occured.
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If an error occured, the global variable
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.Dv errno
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is set to indicate the nature of the failure.
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.Pp
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The functions
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.Fn getgrgid_r ,
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.Fn getgrnam_r ,
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and
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.Fn getgrent_r
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return
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.Dv 0
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on success or entry not found, and non-zero on failure, setting the global
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variable
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.Dv errno
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to indicate the nature of the failure.
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.Pp
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The
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.Fn setgroupent
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function returns the value 1 if successful, otherwise the value
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0 is returned, setting the global variable
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.Dv errno
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to indicate the nature of the failure.
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.Pp
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The
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.Fn endgrent
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and
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.Fn setgrent
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functions 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 alternative group databases, has
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been deprecated and is no longer available.
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.Sh ERRORS
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The following error codes may be set in
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.Va errno
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for
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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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and
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.Nm setgroupent :
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.Bl -tag -width Er
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.It Bq Er EINTR
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A signal was caught during the database search.
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.It Bq Er EIO
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An I/O error has occurred.
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.It Bq Er EMFILE
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The limit on open files for this process has been reached.
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.It Bq Er ENFILE
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The system limit on open files has been reached.
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.El
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.Pp
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The following error code may be set in
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.Va errno
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for
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.Nm getgrent_r ,
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.Nm getgrnam_r ,
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and
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.Nm getgrgid_r :
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.Bl -tag -width Er
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.It Bq Er ERANGE
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The resulting
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.Ft struct group
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does not fit in the space defined by
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.Dv buffer
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and
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.Dv buflen
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.El
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.Pp
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Other
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.Dv errno
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values may be set depending on the specific database backends.
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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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.Sh STANDARDS
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The
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.Fn getgrgid
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and
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.Fn getgrnam
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functions conform to
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.St -p1003.1-90 .
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The
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.Fn getgrgid_r
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and
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.Fn getgrnam_r
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functions conform to
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.St -p1003.1c-95 .
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The
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.Fn endgrent ,
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.Fn getgrent ,
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and
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.Fn setgrent
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functions conform to
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.St -xpg4.2
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and
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.St -p1003.1-2004
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(XSI extension).
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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 getgrgid ,
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.Fn getgrnam ,
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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 getgrgid_r
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and
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.Fn getgrnam_r
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appeared in
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.Nx 3.0 .
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.Sh BUGS
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The functions
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.Fn getgrent ,
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.Fn getgrgid ,
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.Fn getgrnam ,
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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 the same function 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 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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.Fn getgrent
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makes 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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