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 .