[PATCH] resolv.conf(5): Attempt clarify domain/search interaction

[Florian Weimer <fweimer@redhat.com>]

The domain directive is historic at this point; it should not be used.
---
 man5/resolv.conf.5 | 41 ++++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/man5/resolv.conf.5 b/man5/resolv.conf.5
index 49a8eed4c..2ffe973a1 100644
--- a/man5/resolv.conf.5
+++ b/man5/resolv.conf.5
@@ -39,10 +39,9 @@ The configuration file is considered a trusted source of DNS information
 (e.g., DNSSEC AD-bit information will be returned unmodified from this
 source).
 .PP
-If this file does not exist,
-only the name server on the local machine will be queried;
-the domain name is determined from the hostname
-and the domain search path is constructed from the domain name.
+If this file does not exist, only the name server on the local machine
+will be queried, and the search list contains the local domain name
+determined from the hostname.
 .PP
 The different configuration options are:
 .TP
@@ -63,20 +62,14 @@ try the next, until out of name servers,
 then repeat trying all the name servers
 until a maximum number of retries are made.)
 .TP
-\fBdomain\fP Local domain name.
-Most queries for names within this domain can use short names
-relative to the local domain.
-If set to \(aq.\(aq, the root domain is considered.
-If no \fBdomain\fP entry is present, the domain is determined
-from the local hostname returned by
-.BR gethostname (2);
-the domain part is taken to be everything after the first \(aq.\(aq.
-Finally, if the hostname does not contain a domain part, the root
-domain is assumed.
-.TP
 \fBsearch\fP Search list for host-name lookup.
-The search list is normally determined from the local domain name;
-by default, it contains only the local domain name.
+By default, the search list contains one entry, the local domain name.
+It is determined from the local hostname returned by
+.BR gethostname (2);
+the local domain name is taken to be everything after the first
+\(aq.\(aq.  Finally, if the hostname does not contain a \(aq.\(aq, the
+root domain is assumed as the local domain name.
+.IP
 This may be changed by listing the desired domain search path
 following the \fIsearch\fP keyword with spaces or tabs separating
 the names.
@@ -104,11 +97,21 @@ traffic if the servers for the listed domains are not local,
 and that queries will time out if no server is available
 for one of the domains.
 .IP
+If there are multiple
+.B search
+directives, only the search list from the last instance is used.
+.IP
 In glibc 2.25 and earlier, the search list is limited to six domains
 with a total of 256 characters.
 Since glibc 2.26,
 .\" glibc commit 3f853f22c87f0b671c0366eb290919719fa56c0e
 the search list is unlimited.
+.IP
+The
+.B domain
+directive is an obsolete name for the
+.B search
+directive that handles one search list entry only.
 .TP
 \fBsortlist\fP
 This option allows addresses returned by
@@ -315,10 +318,6 @@ in
 This option disables automatic reloading of a changed configuration file.
 .RE
 .PP
-The \fIdomain\fP and \fIsearch\fP keywords are mutually exclusive.
-If more than one instance of these keywords is present,
-the last instance wins.
-.PP
 The \fIsearch\fP keyword of a system's \fIresolv.conf\fP file can be
 overridden on a per-process basis by setting the environment variable
 .B LOCALDOMAIN
-- 
2.21.0