gethostent(3) Library Functions Manual gethostent(3)
NAME
gethostent, gethostent_r, sethostent, sethostent_r - Opens network host file
LIBRARY
Standard C Library (libc.so, libc.a)
SYNOPSIS
#include <netdb.h>
struct hostent *gethostent(void);
void sethostent(
int stay_open);
[Tru64 UNIX] The following obsolete functions are supported in order to maintain backward compatibility with previous versions of the
operating system. You should not use them in new designs. int gethostent_r(
struct hostent *host,
struct hostent_data *host_data);
int sethostent_r(
int stay_open,
struct hostent_data *host_data);
[Tru64 UNIX] The following definition of the sethostent() function does not conform to current standards and is supported only for back-
ward compatibility:
int sethostent(
int stay_open);
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
gethostent(): XNS4.0
sethostent(): XNS4.0
Refer to the standards(5) reference page for more information about industry standards and associated tags.
PARAMETERS
[Tru64 UNIX] For gethostent_r() only, this points to the hostent structure. The netdb.h header file defines the hostent structure.
[Tru64 UNIX] For gethostent_r() and sethostent_r() only, this is data for the host database. The netdb.h header file defines the hos-
tent_data structure. Contains a value used to indicate when to close the network host database. Specifying a value of 0 (zero) closes the
network host database file after each call to the gethostbyname() or gethostbyaddr() function. Specifying a nonzero value allows the net-
work host database file to remain open after each call.
DESCRIPTION
The gethostent() (get host entry) function reads the next line of the either the local /etc/hosts file or one of the files distributed by
BIND or NIS, opening it if necessary, returning a hostent structure. The netdb.h header file defines the hostent_data structure.
The sethostent() (set host entry) function opens either the local /etc/hosts file or one of the files distributed by BIND or NIS, and
resets the file marker to the beginning of the file. To determine which file or files to search, and in which order, the system uses the
switches in the /etc/svc.conf file.
Passing a nonzero value to the stay_open parameter establishes a connection with a name server and allows a client process to retrieve one
entry at a time from the network hosts database file. The client process can close the connection with the endhostent() function.
NOTES
The gethostent() 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 gethostent_r() and sethostent_r() functions are obsolete reentrant versions of the gethostent() and sethostent() func-
tions. They are 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 host_data structure before its first access by the gethostent_r() function.
RETURN VALUES
Upon successful completion, the gethostent() function returns a pointer to a hostent structure. If it fails or reaches the end of the net-
work hostname database, the gethostent() function returns a null pointer and places an appropriate error code in the h_errno variable.
[Tru64 UNIX] Upon successful completion, the gethostent_r() and sethostent_r() functions return a value of 0 (zero). The gethostent_r()
function stores the hostent data structure in the location pointed to by host. Upon failure, the gethostent_r() and sethostent_r() func-
tions return a value of -1 and set the errno variable.
[Tru64 UNIX] The version of sethostent() that is supported for backward compatibility always returns a value of 1.
ERRORS
Current industry standards do not define error values for the gethostent() and sethostent() functions.
[Tru64 UNIX] If the following condition occurs, the gethostent() or gethostent_r() function sets h_errno to the corresponding value: This
error code indicates an unrecoverable error.
[Tru64 UNIX] If the following condition occurs, the gethostent_r() function sets errno to the corresponding value: The host or host_data
parameter is invalid.
[Tru64 UNIX] If the following condition occurs, the sethostent_r() function sets errno to the corresponding value: The host_data parameter
is invalid.
[Tru64 UNIX] In addition, the sethostent(), backward compatible version of sethostent() and sethostent_r() functions can fail to open the
file. In this case errno will be set to the failure.
FILES
Contains the hostname database. Contains the name server and domain name. The database service selection configuration file.
RELATED INFORMATION
Functions: endhostent(3), gethostbyaddr(3), gethostbyname(3)
Files: resolv.conf(4), svc.conf(4)
Networks: bind_intro(7), nis_intro(7)
Standards: standards(5) delim off
gethostent(3)