RWHOD(8) MachTen Programmer’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 net-
work.

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 mes-
sages 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 col-
lection 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 ser-
vices(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 inte-
ger. The host name included is that returned by the geth-
ostname(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 /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.