# 2.11BSD#431 - /usr/man/cat8/rwhod.0

    RWHOD(8)	    UNIX Programmer's Manual		 RWHOD(8)

    NAME
         rwhod - system status server

    SYNOPSIS
         /usr/sbin/rwhod

    DESCRIPTION
         Rwhod is the server which maintains the database used by the
         rwho(1) and ruptime(1) programs.  Its operation is predi-
         cated 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 mes-
         sages 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 located in the directory /usr/spool/rwho.

         The server transmits and receives messages at the port indi-
         cated 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 integer.
         The host name included is that returned by the gethost-
         name(2) system call, with any trailing domain name omitted.
         The array at the end of the message contains information

    Printed 11/26/99	November 16, 1996			1

    RWHOD(8)	    UNIX Programmer's Manual		 RWHOD(8)

         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 termi-
         nal 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.

    SEE ALSO
         rwho(1), ruptime(1)

    BUGS
         There should be a way to relay status information between
         networks. Status information should be sent only upon
         request rather than continuously.	People often interpret
         the server dying or network communtication failures as a
         machine going down.

    Printed 11/26/99	November 16, 1996			2

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