rwhod(8c)rwhod(8c)Namerwhod - system status server
Syntax
/etc/rwhod [ -b ] [ -l ]
Description
The command is the server which maintains the database used by the and
programs. Its operation is predicated on the ability to broadcast mes‐
sages on a network.
The command operates as both a producer and consumer of status informa‐
tion. 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, listens for the status messages of the
other servers, validating them, then recording them in a collection of
files located in the directory
The server transmits and receives messages at the port indicated in the
rwho service specification. For more information, see The messages sent
and received, take the following 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 calculated by the 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 as an
integer. The host name included is the name returned by the 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 send‐
ing machine. This information includes the contents of the entry for
each active terminal line and a value indicating the time since a char‐
acter was last received on the terminal line.
Messages received by the server are discarded unless they originated at
a server's port. In addition, if the host's name, as specified in the
message, contains any unprintable ASCII characters, the message is dis‐
carded. Valid messages received by are placed in files named
whod.fIhostname in the directory These files contain only the most
recent message in the format previously described.
Status messages are generated approximately once every 3 minutes. The
command performs an on every 30 minutes to guard against the possibil‐
ity that this file is not the system image currently operating.
Options-b Sets the broadcast only mode. Sends outgoing packets, but ignores
incoming ones.
-l Sets the listen only mode. Collects incoming packets from the net‐
work, but does not broadcast data.
Restrictions
Because the daemon sends its information in broadcast packets it gener‐
ates a large amount of network traffic. On large networks the extra
traffic may be objectionable. Therefore, the daemon is disabled by
default. To make use of the daemon for both the local and remote
hosts, remove the comment symbols (#) from in front of the lines speci‐
fying in the file.
If the daemon is not running on a remote machine, the machine may
incorrectly appear to be down when you use the command to determine its
status. See the reference page for more information.
If a system has more than 40 users logged in at once, the number of
users displayed by the and commands is incorrect. Users who login
after the fortieth user, will fail to appear in the output of the and
commands. This is because the maximum size limit of an Ethernet packet
is 1500 bytes, and the daemon must broadcast its information in a sin‐
gle packet.
See Alsoruptime(1c), rwho(1c)rwhod(8c)
