RWHOD(8) RWHOD(8)
September 19, 1988
NAME
rwhod - system status server
SYNOPSIS
/etc/rwhod
DESCRIPTION
Rwhod is the server which maintains the database used by the rwho(1C)
and ruptime(1C) programs. Its operation is predicated on the ability
to broadcast messages on a network.
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 /usr/spool/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 {
structoutmp 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
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RWHOD(8) RWHOD(8)
September 19, 1988
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
/usr/spool/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.
SEE ALSO
rwho(1), ruptime(1)
BUGS
There should be a way to relay status information between networks.
Status information should be sent only upon request rather than
continuously. People often interpret the server dying or network
communtication failures as a machine going down.
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