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ENDGRENT(3P)               POSIX Programmer's Manual              ENDGRENT(3P)
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  contain-
       ing the broken-out fields of an entry in the group database. When first
       called, getgrent() shall return a pointer to a group structure contain-
       ing  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  get-
       grent().
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.  Applica-
       tions 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 get-
       grgid() 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 Electri-
       cal  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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                         ENDGRENT(3P)