RWHOD(8C)                                                            RWHOD(8C)



NAME
       rwhod - system status server

SYNOPSIS
       /etc/rwhod

DESCRIPTION
       _R_w_h_o_d  is  the server which maintains the database used by the _r_w_h_o(1C)
       and _r_u_p_t_i_m_e(1C) programs.  Its operation is predicated on  the  ability
       to _b_r_o_a_d_c_a_s_t messages on a network.

       _R_w_h_o_d  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 messages which are broadcast on a network.
       As a consumer of information, it listens for other _r_w_h_o_d servers’  sta‐
       tus  messages,  validating them, then recording them in a collection of
       files located in the directory _/_u_s_r_/_s_p_o_o_l_/_r_w_h_o.

       The server transmits and receives messages at the port indicated in the
       ‘‘rwho’’ service specification; see _s_e_r_v_i_c_e_s(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  _g_e_t_h_o_s_t_‐
       _n_a_m_e(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 _u_t_m_p(5) entry for each non-idle terminal line and a value  indicat‐
       ing the time in seconds since a character was last received on the ter‐
       minal line.

       Messages received by the _r_w_h_o server are discarded unless  they  origi‐
       nated  at  an  _r_w_h_o 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 _r_w_h_o_d are placed
       in files named _w_h_o_d._h_o_s_t_n_a_m_e in the directory  _/_u_s_r_/_s_p_o_o_l_/_r_w_h_o.   These
       files  contain  only  the  most recent message, in the format described
       above.

       Status messages are  generated  approximately  once  every  3  minutes.
       _R_w_h_o_d performs an _n_l_i_s_t(3) on /vmunix every 30 minutes to guard against
       the possibility that this file is not the system image currently  oper‐
       ating.

SEE ALSO
       rwho(1C), ruptime(1C)

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



4.2 Berkeley Distribution        May 24, 1986                        RWHOD(8C)