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 differ (con-
       sult 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 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.

       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(), getpwnam(), or getp-
       went().

       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 pass-
       word database, whether the database is a single file, or where in the file system name space the database resides. Appli-
       cations 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,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                  ENDPWENT(3P)