krw  committed 6fd6ff0

Attempt a short explanation of the resolv.conf dance. A few other
verbiage adjustments.

Fixes from & ok jmc@.

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File sbin/dhclient/dhclient.8

-.\" $OpenBSD: dhclient.8,v 1.18 2013/02/22 22:28:15 krw Exp $
+.\" $OpenBSD: dhclient.8,v 1.19 2013/02/23 11:51:53 krw Exp $
 .\" Copyright (c) 1997 The Internet Software Consortium.
 .\" All rights reserved.
 .\" Enterprises.  To learn more about the Internet Software Consortium,
 .\" see ``''.  To learn more about Vixie
 .\" Enterprises, see ``''.
-.Dd $Mdocdate: February 22 2013 $
+.Dd $Mdocdate: February 23 2013 $
 .Ar interface
 with DHCP.
 The special value
-.Sq egress
+.Dq egress
 may be used instead of a network interface name.
 In this case
 will look for the network interface currently in the interface group
-.Sq egress
+.Dq egress
 and configure it with DHCP.
-If there is more than one network interface in the
-.Sq egress
+If there is more than one network interface in the egress group
 will exit with an error.
 When configuring the interface,
 attempts to remove any existing addresses, gateway routes that use
-the interface and non-permanent
+the interface, and non-permanent
 .Xr arp 8
 Conversely, if the interface is later manipulated to add or delete
 is run on the same interface.
+Once the interface is configured,
+constructs a
+.Xr resolv.conf 5
+It does this only when one or both of the options
+.Cm domain-name
+.Cm domain-name-servers
+is present.
+(note that these options may be offered by the DHCP server but suppressed by
+.Xr dhclient.conf 5 ) .
+If a resolv.conf is contructed,
+appends any contents of the
+.Xr resolv.conf.tail 5
+file, which are read once at start up.
+The constructed resolv.conf is copied into
+.Pa /etc/resolv.conf
+whenever the default route goes out the interface
+is running on.
+monitors the system for changes to the default route and re-checks
+whether it should write its resolv.conf when possible changes are
 In order to keep track of leases across system reboots and server
 While running,
 reacts to a few different signals:
-.Bl -tag -width "USR[12]XXX"
+.Bl -tag -width "USR1, USR2XXX"
 .It Dv HUP
 On receiving
 .Dv HUP
 will exit without attempting to remove any routes, interface addresses
 or temporary files it created.
-.It Dv USR[12]
+.It Dv USR1, USR2
 On receiving either
 .Dv USR1