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

       endhostent, gethostent, sethostent — network host database functions

SYNOPSIS

       #include <netdb.h>

       void endhostent(void);
       struct hostent *gethostent(void);
       void sethostent(int stayopen);

DESCRIPTION

       These  functions shall retrieve information about hosts. This information is considered to be stored in a
       database that can  be  accessed  sequentially  or  randomly.  The  implementation  of  this  database  is
       unspecified.

       Note:     In  many  cases  this  database  is  implemented  by  the  Domain Name System, as documented in
                 RFC 1034, RFC 1035, and RFC 1886.

       The sethostent() function shall open a connection to the database and set the next entry for retrieval to
       the first entry in the database. If the stayopen argument is non-zero, the connection shall not be closed
       by a call to gethostent(), and the implementation may maintain an open file descriptor.

       The gethostent() function shall read the next entry in the database, opening and closing a connection  to
       the database as necessary.

       Entries shall be returned in hostent structures.

       The endhostent() function shall close the connection to the database, releasing any open file descriptor.

       These functions need not be thread-safe.

RETURN VALUE

       Upon  successful  completion,  the gethostent() function shall return a pointer to a hostent structure if
       the requested entry was found, and a null pointer if the end of the database was reached or the requested
       entry was not found.

       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
       gethostent().   The returned pointer, and pointers within the structure, might also be invalidated if the
       calling thread is terminated.

ERRORS

       No errors are defined for endhostent(), gethostent(), and sethostent().

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       endservent()

       The Base Definitions volume of POSIX.1‐2017, <netdb.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 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 .

       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                                   2017                                    ENDHOSTENT(3POSIX)