man.bsd.lv manual page server

DESCRIPTION

Rwhod operates as both a producer and consumer of status information. As a producer of information it periodically queries the state of the system and constructs status messages which are broadcast on a network. As a consumer of information, it listens for other rwhod servers' status messages, validating them, then recording them in a collection of files located in the directory /var/rwho.

The server transmits and receives messages at the port indicated in the ``rwho'' service specification; see services(5). The messages sent and received, are of the form:

struct	outmp {
	char	out_line[8];		/* tty name */
	char	out_name[8];		/* user id */
	long	out_time;		/* time on */
};

struct	whod {
	char	wd_vers;
	char	wd_type;
	char	wd_fill[2];
	int	wd_sendtime;
	int	wd_recvtime;
	char	wd_hostname[32];
	int	wd_loadav[3];
	int	wd_boottime;
	struct	whoent {
		struct	outmp we_utmp;
		int	we_idle;
	} wd_we[1024 / sizeof (struct whoent)];
};

All fields are converted to network byte order prior to transmission. The load averages are as calculated by the w(1) program, and represent load averages over the 5, 10, and 15 minute intervals prior to a server's transmission; they are multiplied by 100 for representation in an integer. The host name included is that returned by the gethostname(2) system call, with any trailing domain name omitted. The array at the end of the message contains information about the users logged in to the sending machine. This information includes the contents of the utmp(5) entry for each non-idle terminal line and a value indicating the time in seconds since a character was last received on the terminal line.

Messages received by the rwho server are discarded unless they originated at an rwho server's port. In addition, if the host's name, as specified in the message, contains any unprintable ASCII characters, the message is discarded. Valid messages received by rwhod are placed in files named whod.hostname in the directory /var/rwho. These files contain only the most recent message, in the format described above.

Status messages are generated approximately once every 3 minutes. Rwhod performs an nlist(3) on /vmunix every 30 minutes to guard against the possibility that this file is not the system image currently operating.