RWHOD(1M) — Series 300 and 800 Only
NAME
rwhod − system status server
SYNOPSIS
/etc/rwhod [ -s ] [ -r ]
DESCRIPTION
Rwhod is the server that maintains the database used by the rwho(1) and ruptime(1) programs. Rwhod sends status information to and receives status information from other nodes on the local network which are running rwhod.
As an information sender, it periodically queries the state of the system and constructs status messages that are broadcast on a network.
As an information receiver, it listens for other rwhod servers’ status messages, validates them and then records them in a collection of files located in the /usr/spool/rwho directory.
By default, rwhod both sends and receives information. Rwhod also supports the following options:
−s Configures server to be an information sender only.
−r Configures server to be an information receiver only.
Status messages are generated approximately once every 3 minutes. Rwhod performs an nlist(3) on /hp-ux every 9 minutes to guard against the possibility that this file is not the system image currently operating.
Rwhod transmits and receives messages at the port indicated in the “who” service specification; see services(4). The messages sent and received, are of the form:
structoutmp {
charout_line[8];/* tty name */
charout_name[8];/* user id */
longout_time;/* time on */
};
structwhod {
charwd_vers;
charwd_type;
charwd_fill[2];
intwd_sendtime;
intwd_recvtime;
charwd_hostname[32];
intwd_loadav[3];
intwd_boottime;
structwhoent {
structoutmp we_utmp;
intwe_idle;
} wd_we[1024 / sizeof (struct whoent)];
};
All fields are converted to network byte order before transmission. System load averages are calculated from the number of jobs in the run queue over the last 1-, 5- and 15-minute intervals. The host name included is that returned by the gethostname(2) system call. The array at the end of the message contains information about the users logged into the sending machine. This information includes the contents of the utmp(7) entry for each non-idle terminal line and a value indicating the time since a character was last received on the terminal line.
Rwhod discards received messages, if they did not originate at a rwho server’s port or if the host’s name, as specified in the message, contains any unprintable ASCII characters.
Valid messages received by rwhod are placed in files named whod.hostname in the /usr/spool/rwho directory. These files contain only the most recent message, in the format described above.
WARNINGS
Rwhod does not relay status information between networks. People often incorrectly interpret the server dying as a machine going down.
DEPENDENCIES
Implemented on the Series 300 and 800 only.
AUTHOR
UCB (University of California at Berkeley)
SEE ALSO
Hewlett-Packard Company — May 11, 2021