1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)rwhod.8 8.1 (Berkeley) 06/06/93 7.\" 8.Dd 9.Dt RWHOD 8 10.Os BSD 4.2 11.Sh NAME 12.Nm rwhod 13.Nd system status server 14.Sh SYNOPSIS 15.Nm rwhod 16.Sh DESCRIPTION 17.Nm Rwhod 18is the server which maintains the database used by the 19.Xr rwho 1 20and 21.Xr ruptime 1 22programs. Its operation is predicated on the ability to 23.Em broadcast 24messages on a network. 25.Pp 26.Nm Rwhod 27operates as both a producer and consumer of status information. 28As a producer of information it periodically 29queries the state of the system and constructs 30status messages which are broadcast on a network. 31As a consumer of information, it listens for other 32.Nm rwhod 33servers' status messages, validating them, then recording 34them in a collection of files located in the directory 35.Pa /var/rwho . 36.Pp 37The server transmits and receives messages at the port indicated 38in the ``rwho'' service specification; see 39.Xr services 5 . 40The messages sent and received, are of the form: 41.Bd -literal -offset indent 42struct outmp { 43 char out_line[8]; /* tty name */ 44 char out_name[8]; /* user id */ 45 long out_time; /* time on */ 46}; 47 48struct whod { 49 char wd_vers; 50 char wd_type; 51 char wd_fill[2]; 52 int wd_sendtime; 53 int wd_recvtime; 54 char wd_hostname[32]; 55 int wd_loadav[3]; 56 int wd_boottime; 57 struct whoent { 58 struct outmp we_utmp; 59 int we_idle; 60 } wd_we[1024 / sizeof (struct whoent)]; 61}; 62.Ed 63.Pp 64All fields are converted to network byte order prior to 65transmission. The load averages are as calculated by the 66.Xr w 1 67program, and represent load averages over the 5, 10, and 15 minute 68intervals prior to a server's transmission; they are multiplied by 100 69for representation in an integer. The host name 70included is that returned by the 71.Xr gethostname 2 72system call, with any trailing domain name omitted. 73The array at the end of the message contains information about 74the users logged in to the sending machine. This information 75includes the contents of the 76.Xr utmp 5 77entry for each non-idle terminal line and a value indicating the 78time in seconds since a character was last received on the terminal line. 79.Pp 80Messages received by the 81.Xr rwho 82server are discarded unless they originated at an 83.Xr rwho 84server's port. In addition, if the host's name, as specified 85in the message, contains any unprintable 86.Tn ASCII 87characters, the 88message is discarded. Valid messages received by 89.Nm rwhod 90are placed in files named 91.Pa whod.hostname 92in the directory 93.Pa /var/rwho . 94These files contain only the most recent message, in the 95format described above. 96.Pp 97Status messages are generated approximately once every 983 minutes. 99.Nm Rwhod 100performs an 101.Xr nlist 3 102on 103.Pa /vmunix 104every 30 minutes to guard against 105the possibility that this file is not the system 106image currently operating. 107.Sh SEE ALSO 108.Xr rwho 1 , 109.Xr ruptime 1 110.Sh BUGS 111There should be a way to relay status information between networks. 112Status information should be sent only upon request rather than continuously. 113People often interpret the server dying 114or network communtication failures 115as a machine going down. 116.Sh HISTORY 117The 118.Nm 119command appeared in 120.Bx 4.2 . 121