listing for G
gethostbyname, gethostbyname_r - Get a network host entry by name
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 system. You
should not use it in new designs.
const char *name,
struct hostent *hptr,
struct hostent_data *hdptr );
Standard C Library (libc)
Interfaces documented on this reference page conform to industry standards
gethostbyname(): XNS4.0, XNS5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
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.
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:
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.
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()
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.
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
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.
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.
Functions: endhostent(3), gethostbyaddr(3), sethostent(3).
Files: hostname(5), resolv.conf(4), svc.conf(4).
Networks: bind_intro(7), nis_intro(7).
Network Programmer's Guide
listing for G