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fbbd9655e5
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
240 lines
6.5 KiB
Groff
240 lines
6.5 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)rwhod.8 8.2 (Berkeley) 12/11/93
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.\" $FreeBSD$
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.\"
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.Dd January 21, 2010
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.Dt RWHOD 8
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.Os
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.Sh NAME
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.Nm rwhod
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.Nd system status server
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.Sh SYNOPSIS
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.Nm
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.Op Fl i
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.Op Fl p
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.Op Fl l
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.Op Fl m Op Ar ttl
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.Sh DESCRIPTION
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The
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.Nm
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utility is the server which maintains the database used by the
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.Xr rwho 1
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and
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.Xr ruptime 1
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programs.
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Its operation is predicated on the ability to
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.Em broadcast
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or
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.Em multicast
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messages on a network.
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.Pp
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The
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.Nm
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utility operates as both a producer and consumer of status information,
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unless the
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.Fl l
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(listen mode) option is specified, in which case
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it acts as a consumer only.
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As a producer of information it periodically
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queries the state of the system and constructs
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status messages which are broadcasted or multicasted on a network.
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As a consumer of information, it listens for other
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.Nm
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servers' status messages, validating them, then recording
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them in a collection of files located in the directory
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.Pa /var/rwho .
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.Pp
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The following options are available:
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.Bl -tag -width indent
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.It Fl i
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Enable insecure mode, which causes
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.Nm
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to ignore the source port on incoming packets.
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.It Fl p
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Ignore all
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.Dv POINTOPOINT
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interfaces.
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This is useful if you do not wish to keep dial on demand
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interfaces permanently active.
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.It Fl l
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Enable listen mode, which causes
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.Nm
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to not broadcast any information.
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This allows you to monitor other machines'
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.Nm
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information, without broadcasting your own.
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.It Fl m Op Ar ttl
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Cause
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.Nm
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to use IP multicast (instead of
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broadcast) on all interfaces that have
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the IFF_MULTICAST flag set in their "ifnet" structs
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(excluding the loopback interface).
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The multicast
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reports are sent with a time-to-live of 1, to prevent
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forwarding beyond the directly-connected subnet(s).
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.Pp
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If the optional
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.Ar ttl
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argument is supplied with the
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.Fl m
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flag,
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.Nm
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will send IP multicast datagrams with a
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time-to-live of
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.Ar ttl ,
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via a SINGLE interface rather
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than all interfaces.
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.Ar ttl
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must be between 0 and
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32 (or MAX_MULTICAST_SCOPE).
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Note that
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.Fl m Ar 1
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is different from
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.Fl m ,
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in that
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.Fl m Ar 1
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specifies transmission on one interface only.
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.Pp
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When
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.Fl m
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is used without a
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.Ar ttl
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argument, the program accepts multicast
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.Nm
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reports from all multicast-capable interfaces.
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If a
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.Ar ttl
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argument is given, it accepts multicast reports from only one interface, the
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one on which reports are sent (which may be controlled via the host's routing
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table).
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Regardless of the
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.Fl m
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option, the program accepts broadcast or
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unicast reports from all interfaces.
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Thus, this program will hear the
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reports of old, non-multicasting
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.Nm Ns s ,
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but, if multicasting is used,
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those old
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.Nm Ns s
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will not hear the reports generated by this program.
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.El
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.Pp
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The server transmits and receives messages at the port indicated
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in the ``who'' service specification; see
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.Xr services 5 .
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The messages sent and received, are of the form:
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.Bd -literal -offset indent
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struct outmp {
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char out_line[8]; /* tty name */
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char out_name[8]; /* user id */
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long out_time; /* time on */
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};
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struct whod {
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char wd_vers;
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char wd_type;
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char wd_fill[2];
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int wd_sendtime;
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int wd_recvtime;
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char wd_hostname[32];
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int wd_loadav[3];
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int wd_boottime;
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struct whoent {
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struct outmp we_utmp;
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int we_idle;
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} wd_we[1024 / sizeof (struct whoent)];
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};
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.Ed
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.Pp
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All fields are converted to network byte order prior to
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transmission.
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The load averages are as calculated by the
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.Xr w 1
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program, and represent load averages over the 5, 10, and 15 minute
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intervals prior to a server's transmission; they are multiplied by 100
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for representation in an integer.
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The host name
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included is that returned by the
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.Xr gethostname 3
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system call, with any trailing domain name omitted.
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The array at the end of the message contains information about
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the users logged in to the sending machine.
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This information
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includes the contents of the entry from the user accounting database
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for each non-idle terminal line and a value indicating the
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time in seconds since a character was last received on the terminal line.
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.Pp
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Messages received by the
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.Nm rwho
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server are discarded unless they originated at an
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.Nm rwho
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server's port or the
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.Fl i
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option was specified.
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In addition, if the host's name, as specified
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in the message, contains any unprintable
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.Tn ASCII
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characters, the
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message is discarded.
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Valid messages received by
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.Nm
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are placed in files named
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.Pa whod.hostname
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in the directory
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.Pa /var/rwho .
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These files contain only the most recent message, in the
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format described above.
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.Pp
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Status messages are generated approximately once every
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3 minutes.
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The
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.Nm
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utility performs an
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.Xr nlist 3
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on
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.Pa /boot/kernel/kernel
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every 30 minutes to guard against
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the possibility that this file is not the system
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image currently operating.
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.Sh SEE ALSO
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.Xr ruptime 1 ,
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.Xr rwho 1
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Bx 4.2 .
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.Sh BUGS
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Status information should be sent only upon request rather than continuously.
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People often interpret the server dying
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or network communication failures
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as a machine going down.
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