371 lines
8.3 KiB
Groff
371 lines
8.3 KiB
Groff
.\" $NetBSD: getpwent.3,v 1.38 2011/04/28 16:35:05 wiz Exp $
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.\"
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.\" Copyright (c) 1988, 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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.\" @(#)getpwent.3 8.2 (Berkeley) 12/11/93
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.\"
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.Dd April 30, 2008
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.Dt GETPWENT 3
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.Os
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.Sh NAME
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.Nm getpwent ,
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.Nm getpwent_r ,
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.Nm getpwnam ,
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.Nm getpwnam_r ,
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.Nm getpwuid ,
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.Nm getpwuid_r ,
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.Nm setpassent ,
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.Nm setpwent ,
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.Nm endpwent
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.Nd password 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 pwd.h
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.Ft struct passwd *
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.Fn getpwent void
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.Ft int
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.Fo getpwent_r
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.Fa "struct passwd *pw"
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.Fa "char *buffer"
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.Fa "size_t buflen"
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.Fa "struct passwd **result"
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.Fc
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.Ft struct passwd *
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.Fn getpwnam "const char *name"
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.Ft int
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.Fo getpwnam_r
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.Fa "const char *name"
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.Fa "struct passwd *pw"
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.Fa "char *buffer"
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.Fa "size_t buflen"
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.Fa "struct passwd **result"
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.Fc
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.Ft struct passwd *
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.Fn getpwuid "uid_t uid"
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.Ft int
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.Fo getpwuid_r
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.Fa "uid_t uid"
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.Fa "struct passwd *pw"
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.Fa "char *buffer"
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.Fa "size_t buflen"
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.Fa "struct passwd **result"
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.Fc
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.Ft int
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.Fn setpassent "int stayopen"
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.Ft void
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.Fn setpwent void
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.Ft void
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.Fn endpwent void
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.Sh DESCRIPTION
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These functions
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operate on the password database
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which is described
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in
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.Xr passwd 5 .
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Each entry in the database is defined by the structure
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.Ar passwd
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found in the include
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file
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.In pwd.h :
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.Bd -literal -offset indent
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struct passwd {
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char *pw_name; /* user name */
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char *pw_passwd; /* encrypted password */
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uid_t pw_uid; /* user uid */
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gid_t pw_gid; /* user gid */
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time_t pw_change; /* password change time */
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char *pw_class; /* user login class */
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char *pw_gecos; /* general information */
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char *pw_dir; /* home directory */
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char *pw_shell; /* default shell */
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time_t pw_expire; /* account expiration */
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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 getpwnam
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and
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.Fn getpwuid
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search the password database for the given user name pointed to by
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.Ar name
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or user id pointed to by
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.Ar uid
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respectively, always returning the first one encountered.
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Identical user names or user ids may result in undefined behavior.
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.Pp
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The
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.Fn getpwent
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function
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sequentially reads the password database and is intended for programs
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that wish to process the complete list of users.
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.Pp
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The functions
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.Fn getpwnam_r ,
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.Fn getpwuid_r ,
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and
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.Fn getpwent_r
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act like their non re-entrant counterparts, updating the contents of
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.Ar pw
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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 pw
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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 getpwent_r
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from multiple threads will result in each thread reading a disjoint portion
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of the password database.
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.Pp
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The
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.Fn setpassent
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function
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accomplishes two purposes.
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First, it causes
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.Fn getpwent
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to
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.Dq rewind
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to the beginning of the database.
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Additionally, 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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up subsequent accesses for all of the functions.
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(This latter functionality is unnecessary for
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.Fn getpwent
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as it doesn't close its file descriptors by default.)
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.Pp
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It is dangerous for long-running programs to keep the file descriptors
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open as the database will become out of date if it is updated while the
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program is running.
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.Pp
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The
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.Fn setpwent
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function
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is equivalent to
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.Fn setpassent
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with an argument of zero.
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.Pp
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The
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.Fn endpwent
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function
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closes any open files.
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.Pp
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These functions have been written to
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.Dq shadow
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the password file, e.g. allow only certain programs to have access
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to the encrypted password.
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If the process which calls them has an effective uid of 0, the encrypted
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password will be returned, otherwise, the password field of the returned
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structure will point to the string
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.Ql * .
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.Sh RETURN VALUES
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The functions
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.Fn getpwent ,
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.Fn getpwnam ,
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and
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.Fn getpwuid ,
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return a valid pointer to a passwd 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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The
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.Fn setpassent
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function returns 0 on failure, setting the global variable
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.Dv errno
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to indicate the nature of the failure, and 1 on success.
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The
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.Fn endpwent
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and
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.Fn setpwent
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functions
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have no return value.
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The functions
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.Fn getpwnam_r ,
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.Fn getpwuid_r ,
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and
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.Fn getpwent_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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.Sh FILES
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.Bl -tag -width /etc/master.passwd -compact
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.It Pa /etc/pwd.db
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The insecure password database file
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.It Pa /etc/spwd.db
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The secure password database file
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.It Pa /etc/master.passwd
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The current password file
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.It Pa /etc/passwd
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A Version 7 format password file
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.El
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.Sh COMPATIBILITY
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The historic function
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.Fn setpwfile
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which allowed the specification of alternative password databases,
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has 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 getpwent ,
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.Nm getpwent_r ,
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.Nm getpwnam ,
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.Nm getpwnam_r ,
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.Nm getpwuid ,
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.Nm getpwuid_r ,
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and
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.Nm setpassent :
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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 getpwent_r ,
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.Nm getpwnam_r ,
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and
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.Nm getpwuid_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 passwd
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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 getlogin 2 ,
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.Xr getgrent 3 ,
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.Xr nsswitch.conf 5 ,
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.Xr passwd 5 ,
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.Xr passwd.conf 5 ,
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.Xr pwd_mkdb 8 ,
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.Xr vipw 8
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.Sh STANDARDS
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The
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.Fn getpwnam
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and
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.Fn getpwuid ,
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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 getpwnam_r
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and
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.Fn getpwuid_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 endpwent ,
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.Fn getpwent ,
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and
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.Fn setpwent
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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
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.Nm getpwent ,
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.Nm getpwnam ,
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.Nm getpwuid ,
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.Nm setpwent ,
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and
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.Nm endpwent
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functions appeared in
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.At v7 .
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The
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.Nm setpassent
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function appeared in
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.Bx 4.3 Reno .
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The functions
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.Fn getpwnam_r
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and
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.Fn getpwuid_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 getpwent ,
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.Fn getpwnam ,
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and
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.Fn getpwuid ,
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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 any of these functions will modify the same object.
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.Pp
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The functions
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.Fn getpwent ,
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.Fn endpwent ,
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.Fn setpassent ,
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and
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.Fn setpwent
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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 getpwent
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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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