.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "ENDPWENT" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" endpwent 
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.SH NAME
endpwent, getpwent, setpwent \- user database functions
.SH SYNOPSIS
.LP
\fB#include <pwd.h>
.br
.sp
void endpwent(void);
.br
struct passwd *getpwent(void);
.br
void setpwent(void); \fP
\fB
.br
\fP
.SH DESCRIPTION
.LP
These functions shall retrieve information about users.
.LP
The \fIgetpwent\fP() function shall return a pointer to a structure
containing the broken-out fields of an entry in the user
database. Each entry in the user database contains a \fBpasswd\fP
structure. When first called, \fIgetpwent\fP() shall return a
pointer to a \fBpasswd\fP structure containing the first entry in
the user database. Thereafter, it shall return a pointer to a
\fBpasswd\fP structure containing the next entry in the user database.
Successive calls can be used to search the entire user
database.
.LP
If an end-of-file or an error is encountered on reading, \fIgetpwent\fP()
shall return a null pointer.
.LP
An implementation that provides extended security controls may impose
further implementation-defined restrictions on accessing
the user database. In particular, the system may deny the existence
of some or all of the user database entries associated with
users other than the caller.
.LP
The \fIsetpwent\fP() function effectively rewinds the user database
to allow repeated searches.
.LP
The \fIendpwent\fP() function may be called to close the user database
when processing is complete.
.LP
These functions need not be reentrant. A function that is not required
to be reentrant is not required to be thread-safe.
.SH RETURN VALUE
.LP
The \fIgetpwent\fP() function shall return a null pointer on end-of-file
or error.
.SH ERRORS
.LP
The \fIgetpwent\fP(), \fIsetpwent\fP(), and \fIendpwent\fP() functions
may fail if:
.TP 7
.B EIO
An I/O error has occurred.
.sp
.LP
In addition, \fIgetpwent\fP() and \fIsetpwent\fP() may fail if:
.TP 7
.B EMFILE
{OPEN_MAX} file descriptors are currently open in the calling process.
.TP 7
.B ENFILE
The maximum allowable number of files is currently open in the system.
.sp
.LP
The return value may point to a static area which is overwritten by
a subsequent call to \fIgetpwuid\fP(), \fIgetpwnam\fP(), or
\fIgetpwent\fP().
.br
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.SS Searching the User Database
.LP
The following example uses the \fIgetpwent\fP() function to get successive
entries in the user database, returning a pointer to
a \fBpasswd\fP structure that contains information about each user.
The call to \fIendpwent\fP() closes the user database and
cleans up.
.sp
.RS
.nf

\fB#include <pwd.h>
\&...
struct passwd *p;
\&...
while ((p = getpwent ()) != NULL) {
\&...
}
.sp

endpwent();
\&...
\fP
.fi
.RE
.SH APPLICATION USAGE
.LP
These functions are provided due to their historical usage. Applications
should avoid dependencies on fields in the password
database, whether the database is a single file, or where in the file
system name space the database resides. Applications should
use \fIgetpwuid\fP() whenever possible because it avoids these dependencies.
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIendgrent\fP(), \fIgetlogin\fP(), \fIgetpwnam\fP(), \fIgetpwuid\fP(),
the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, \fI<pwd.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .