gethostbyname man page on YellowDog

Man page or keyword search:  
man Server   18644 pages
apropos Keyword Search (all sections)
Output format
YellowDog logo
[printable version]

GETHOSTBYADDR(P)	   POSIX Programmer's Manual	      GETHOSTBYADDR(P)

NAME
       gethostbyaddr, gethostbyname - network host database functions

SYNOPSIS
       #include <netdb.h>

       struct hostent *gethostbyaddr(const void *addr, socklen_t len,
	      int type);
       struct hostent *gethostbyname(const char *name);

DESCRIPTION
       These  functions	 shall retrieve information about hosts. This informa‐
       tion is considered to be stored in a  database  that  can  be  accessed
       sequentially  or	 randomly. Implementation of this database is unspeci‐
       fied.

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

       Entries shall be returned in hostent structures.

       The gethostbyaddr() function shall return an entry containing addresses
       of address family type for the host with address addr. The len argument
       contains	 the  length  of  the address pointed to by addr. The gethost‐
       byaddr() function need  not  be	reentrant.  A  function	 that  is  not
       required to be reentrant is not required to be thread-safe.

       The gethostbyname() function shall return an entry containing addresses
       of address family AF_INET for the host with name name.  The  gethostby‐
       name() function need not be reentrant.  A function that is not required
       to be reentrant is not required to be thread-safe.

       The addr argument of gethostbyaddr() shall be an in_addr structure when
       type  is AF_INET. It contains a binary format (that is, not null-termi‐
       nated) address in network byte order. The gethostbyaddr()  function  is
       not  guaranteed	to  return  addresses  of  address families other than
       AF_INET, even when such addresses exist in the database.

       If gethostbyaddr() returns successfully, then the h_addrtype  field  in
       the  result  shall  be the same as the type argument that was passed to
       the function, and the h_addr_list field shall  list  a  single  address
       that is a copy of the addr argument that was passed to the function.

       The name argument of gethostbyname() shall be a node name; the behavior
       of gethostbyname() when passed a numeric address string is unspecified.
       For IPv4, a numeric address string shall be in the dotted-decimal nota‐
       tion described in inet_addr() .

       If name is not a numeric address string and is an  alias	 for  a	 valid
       host name, then gethostbyname() shall return information about the host
       name to which the alias refers, and name shall be included in the  list
       of aliases returned.

RETURN VALUE
       Upon successful completion, these functions 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.

       Upon unsuccessful completion, gethostbyaddr() and gethostbyname() shall
       set h_errno to indicate the error.

ERRORS
       These  functions shall fail in the following cases. The gethostbyaddr()
       and gethostbyname() functions shall set h_errno to the value  shown  in
       the list below. Any changes to errno are unspecified.

       HOST_NOT_FOUND

	      No such host is known.

       NO_DATA
	      The  server  recognized the request and the name, but no address
	      is available. Another type of request to the name server for the
	      domain might return an answer.

       NO_RECOVERY

	      An unexpected server failure occurred which cannot be recovered.

       TRY_AGAIN
	      A	 temporary  and	 possibly  transient error occurred, such as a
	      failure of a server to respond.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The gethostbyaddr() and gethostbyname() functions may  return  pointers
       to  static data, which may be overwritten by subsequent calls to any of
       these functions.

       The getaddrinfo() and getnameinfo() functions are  preferred  over  the
       gethostbyaddr() and gethostbyname() functions.

RATIONALE
       None.

FUTURE DIRECTIONS
       The gethostbyaddr() and gethostbyname() functions may be withdrawn in a
       future version.

SEE ALSO
       endhostent()  ,	endservent()  ,	 gai_strerror()	 ,   getaddrinfo()   ,
       h_errno()   ,   inet_addr()   ,	 the   Base   Definitions   volume  of
       IEEE Std 1003.1-2001, <netdb.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 .

IEEE/The Open Group		     2003		      GETHOSTBYADDR(P)
[top]

List of man pages available for YellowDog

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net