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

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 contain‐
       ing 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 data‐
       base. In particular, the system may deny the existence of some  or  all
       of the user database entries associated with users other than the call‐
       er.

       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 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.  Applica‐
       tions  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  Defini‐
       tions 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, 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 .

IEEE/The Open Group		     2003			   ENDPWENT(P)
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