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 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,
       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)