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.
In many cases this database is implemented by the Domain
Name System, as documented in RFC 1034, RFC 1035, and
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(), gethostbyname(), or
gethostbyaddr(), and the implementation may maintain an open file
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. Refer to
gethostbyaddr() for a definition of the hostent structure.
The endhostent() function shall close the connection to the database,
releasing any open file descriptor.
These functions need not be reentrant. A function that is not required to be
reentrant is not required to be thread-safe.
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
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