RWHOD(8) BSD System Manager's Manual RWHOD(8) NNAAMMEE rrwwhhoodd - system status server SSYYNNOOPPSSIISS rrwwhhoodd DDEESSCCRRIIPPTTIIOONN RRwwhhoodd is the server which maintains the database used by the rwho(1) and ruptime(1) programs. Its operation is predicated on the ability to _b_r_o_a_d_c_a_s_t messages on a network. RRwwhhoodd 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 rrwwhhoodd servers' status mes- sages, validating them, then recording them in a collection of files lo- cated in the directory _/_v_a_r_/_r_w_h_o. The server transmits and receives messages at the port indicated in the ``rwho'' service specification; see services(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 { 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 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 inte- ger. The host name included is that returned by the gethostname(2) sys- tem 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 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 terminal 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 rrwwhhoodd are placed in files named _w_h_o_d_._h_o_s_t_n_a_m_e in the directory _/_v_a_r_/_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. RRwwhhoodd performs an nlist(3) on _/_v_m_u_n_i_x every 30 minutes to guard against the possibility that this file is not the system image currently operating. SSEEEE AALLSSOO rwho(1), ruptime(1) BBUUGGSS There should be a way to relay status information between networks. Sta- tus information should be sent only upon request rather than continuous- ly. People often interpret the server dying or network communtication failures as a machine going down. HHIISSTTOORRYY The rrwwhhoodd command appeared in 4.2BSD. 4.2 Berkeley Distribution June 6, 1993 2