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endgrent(3posix)


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.12008, <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 .



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