gethostbyname(3)					     Library Functions Manual						  gethostbyname(3)

NAME

       gethostbyname, gethostbyname_r - Get a network host entry by name

LIBRARY

       Standard C Library (libc.so, libc.a)

SYNOPSIS

       #include <netdb.h>

       struct hostent *gethostbyname(	   const char *name);

       [Tru64  UNIX]  The following function is supported in order to maintain backward compatibility with previous versions of the operating sys-
       tem.  You should not use it in new designs.  int gethostbyname_r(      const  char  *name,	struct	hostent  *hptr,       struct  hos-
       tent_data *hdptr);

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       gethostbyname():  XNS4.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Specifies the official network name or alias.  [Tru64 UNIX]  For gethostbyname_r() only, this points to the hostent structure.  The netdb.h
       header file defines hostent structure.  [Tru64 UNIX]  For gethostbyname_r() only, this is data for hosts database.  The netdb.h header file
       defines hostent_data structure.

DESCRIPTION

       The  gethostbyname()  function  returns	a pointer to a structure of type hostent.  Its members specify data obtained from either the local
       /etc/hosts file or one of the files distributed by DNS/BIND or NIS.  To determine which file or files to search, and in	which  order,  the
       system uses the switches in the /etc/svc.conf file.  The netdb.h header file defines the hostent structure.

       If using DNS/BIND, the information is obtained from a name server specified in the /etc/resolv.conf file.

       If  the	name  parameter does not contain a dot "." and you are using DNS/BIND, the gethostbyname() function checks whether the environment
       variable HOSTALIASES is set.  If set, it first searches the file named by HOSTALIASES for an alias matching the name parameter.	The  alias
       file  has  the following format: name1 name2 The alias name.  This name cannot include dots.  The host name used by DNS/BIND to look up the
       host information.  The hosts database must be distributed by DNS/BIND.

NOTES

       The gethostbyname() function returns a pointer to thread-specific data.	Subsequent calls to this or  a	related  function  from  the  same
       thread overwrite this data.

       [Tru64 UNIX]  The gethostbyname_r() function is an obsolete reentrant version of the gethostbyname() function.  It is supported in order to
       maintain backward compatibility with previous versions of the operating system and should not be used in new designs.  Note that  you  must
       zero-fill the hdptr structure before its first access by the gethostbyname_r() function.

RETURN VALUES

       Upon  successful  completion,  the gethostbyname() function returns a pointer to a hostent structure.  If it reaches the end of the network
       host name database, it returns a null pointer.

       [Tru64 UNIX]  Upon successful completion, the gethostbyname_r() function stores the hostent structure in the location pointed to  by  hptr,
       and returns a value of 0 (zero).  Upon failure, it returns a value of -1.

ERRORS

       If  the gethostbyname() or gethostbyname_r() function call fails,  h_errno is set to one of the following the values: Host is unknown.  The
       server recognized the request and the name, but no address is available for the name.  Another type of name server request may be  success-
       ful.   An unexpected server failure occurred.  This is a nonrecoverable error.  A transient error occurred, for example, the server did not
       respond.  A retry at some later time may be successful.

       [Tru64 UNIX]  If any of the following conditions occurs, the gethostbyaddr_r() function sets errno to the corresponding	value:	The  name,
       hptr, or hdptr is invalid.

FILES

       The  Internet  network  host  name  database.  Each  record  in the file occupies a single line and has three fields consisting of the host
       address, official host name, and aliases.  The resolver configuration file.  The database service selection configuration file.

RELATED INFORMATION

       Functions: endhostent(3), gethostbyaddr(3), sethostent(3).

       Files: hostname(5), resolv.conf(4), svc.conf(4).

       Networks: bind_intro(7), nis_intro(7).

       Standards: standards(5) delim off

																  gethostbyname(3)