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ENDPWENT(3P)               POSIX Programmer's Manual              ENDPWENT(3P)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (consult the corresponding Linux manual page for details of Linux behavior), or the interface  may  not  be
       implemented on Linux.

NAME
       endpwent, getpwent, setpwent - user database functions

SYNOPSIS
       #include <pwd.h>

       void endpwent(void);
       struct passwd *getpwent(void);
       void setpwent(void);


DESCRIPTION
       These functions shall retrieve information about users.

       The  getpwent()  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 passwd structure. When first  called,  getpwent()
       shall  return  a  pointer to a passwd structure containing the first entry in the user database. Thereafter, it
       shall return a pointer to a passwd structure containing the next entry in the user database.  Successive  calls
       can be used to search the entire user database.

       If an end-of-file or an error is encountered on reading, getpwent() shall return a null pointer.

       An  implementation  that provides extended security controls may impose further implementation-defined restric-
       tions 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.

       The setpwent() function effectively rewinds the user database to allow repeated searches.

       The endpwent() function may be called to close the user database when processing is complete.

       These  functions  need  not be reentrant. A function that is not required to be reentrant is not required to be
       thread-safe.

RETURN VALUE
       The getpwent() function shall return a null pointer on end-of-file or error.

ERRORS
       The getpwent(), setpwent(), and endpwent() functions may fail if:

       EIO    An I/O error has occurred.


       In addition, getpwent() and setpwent() may fail if:

       EMFILE {OPEN_MAX} file descriptors are currently open in the calling process.

       ENFILE The maximum allowable number of files is currently open in the system.


       The return value may point to a static area which is overwritten by a subsequent  call  to  getpwuid(),  getpw-
       nam(), or getpwent().

       The following sections are informative.

EXAMPLES
   Searching the User Database
       The  following example uses the getpwent() function to get successive entries in the user database, returning a
       pointer to a passwd structure that contains information about each user.  The call  to  endpwent()  closes  the
       user database and cleans up.


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


              endpwent();
              ...

APPLICATION USAGE
       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 getpwuid() whenever possible because it avoids these dependencies.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       endgrent(), getlogin(), getpwnam(), getpwuid(), the Base Definitions volume of IEEE Std 1003.1-2001, <pwd.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base  Specifica-
       tions  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 Stan-
       dard,  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 .



IEEE/The Open Group                  2003                         ENDPWENT(3P)