RWHOD(8C) RWHOD(8C) NAME rwhod - system status server SYNOPSIS /etc/rwhod DESCRIPTION Rwhod is the server which maintains the database used by the rwho(1C) and ruptime(1C) programs. Its operation is predicated 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 messages which are broadcast on a network. As a consumer of information, it listens for other rwhod servers’ sta‐ tus messages, 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 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 { 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 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 indicat‐ ing the time in seconds since a character was last received on the ter‐ minal line. Messages received by the rwho server are discarded unless they origi‐ nated 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 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)