rwhod(1M)                                                         rwhod(1M)

NAME
     rwhod, in.rwhod - system status server

SYNOPSIS
     in.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 generates status information itself and processes status infor-
     mation generated by other rwhod daemons. It periodically queries the
     system status and generates status messages which are broadcast to all
     systems on the network. It listens for status messages from other
     rwhod servers in the network validates them, then records them in a
     collection of files located in the directory /var/spool/rwho.

     The rwhod server transmits and receives messages at the port indicated
     in the rwho service specification, see services(4). The messages sent
     and received, are of the form:

     struct    outmp {
             char    outline[8];    /* tty name */
             char    outname[8];    /* user id */
             long    outtime;       /* time on */
     };

     struct    whod {
             char    wdvers;
             char    wdtype;
             char    wdfill[2];
             int     wdsendtime;
             int     wdrecvtime;
             char    wdhostname[32];
             int     wdloadav[3];
             int     wdboottime;
                     struct  whoent {
                     struct  outmp weutmp;
                     int     weidle;
             } wdwe[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. The host name included is that returned by the
     gethostname(3N) system call. The array at the end of the message con-
     tains information about the users logged in to the sending machine.
     This information includes the contents of the utmp(4) entry for each
     non-idle terminal line and a value indicating the time since a charac-
     ter was last received on the terminal line.



Page 1                       Reliant UNIX 5.44                Printed 11/98

rwhod(1M)                                                         rwhod(1M)

     Messages received by the rwho server are discarded unless they ori-
     ginated at a 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/spool/rwho. These
     files contain only the most recent message, in the format described
     above.

     Status messages are generated approximately once every 60 seconds.
     rwhod performs an nlist(3E) on /stand/unix every 10 minutes to guard
     against the possibility that this file is not the system image
     currently operating.

NOTES
     This service takes up progressively more network bandwidth as the
     number of hosts on the local net increases. For large networks, the
     cost becomes prohibitive.

     rwhod should relay status information between networks. People often
     interpret the server dying as a machine going down.

FILES
     /var/spool/rwho

SEE ALSO
     rwho(1), ruptime(1), w(1), nlist(3E), gethostname(3N), utmp(4).




























Page 2                       Reliant UNIX 5.44                Printed 11/98