RWHOD(8) MachTen System Manager’s Manual RWHOD(8)

NAME
rwhod - system status server

SYNOPSIS
rwhod

DESCRIPTION
Rwhod is the server which maintains the database used by the rwho(1) and
ruptime(1) 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 mes-
sages, validating them, then recording them in a collection of files lo-
cated 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 inte-
ger. The host name included is that returned by the gethostname(2) sys-
tem 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.