PROLOG

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

NAME

       endgrent, getgrent, setgrent — group database entry functions

SYNOPSIS

       #include <grp.h>

       void endgrent(void);
       struct group *getgrent(void);
       void setgrent(void);

DESCRIPTION

       The  getgrent()  function  shall  return  a pointer to a structure containing the broken-out fields of an
       entry in the group database. When first called, getgrent() shall return a pointer to  a  group  structure
       containing  the  first  entry  in  the  group  database. Thereafter, it shall return a pointer to a group
       structure containing the next group structure in the group database, so successive calls may be  used  to
       search the entire database.

       An  implementation  that  provides  extended  security controls may impose further implementation-defined
       restrictions on accessing the group database. In particular, the system may deny the existence of some or
       all of the group database entries associated with groups other than  those  groups  associated  with  the
       caller  and  may  omit users other than the caller from the list of members of groups in database entries
       that are returned.

       The setgrent() function shall rewind the group database to allow repeated searches.

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

       These functions need not be thread-safe.

RETURN VALUE

       When first called, getgrent() shall return a pointer to the first group structure in the group  database.
       Upon  subsequent  calls  it  shall  return the next group structure in the group database. The getgrent()
       function shall return a null pointer on end-of-file or an error and errno may  be  set  to  indicate  the
       error.

       The  application  shall  not modify the structure to which the return value points, nor any storage areas
       pointed to by pointers within the structure. The returned pointer, and  pointers  within  the  structure,
       might  be  invalidated or the structure or the storage areas might be overwritten by a subsequent call to
       getgrgid(), getgrnam(), or getgrent().

ERRORS

       The getgrent() function may fail if:

       EINTR  A signal was caught during the operation.

       EIO    An I/O error has occurred.

       EMFILE All file descriptors available to the process are currently open.

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

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       These functions are provided due to their historical usage.  Applications should  avoid  dependencies  on
       fields  in  the  group  database, whether the database is a single file, or where in the file system name
       space the database resides. Applications should use getgrnam() and getgrgid() whenever  possible  because
       it avoids these dependencies.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       endpwent(), getgrgid(), getgrnam(), getlogin()

       The Base Definitions volume of POSIX.1‐2008, <grp.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers,  Inc
       and  The  Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2013                                      ENDGRENT(3POSIX)