Correct documentation error: in 8.1 and 8.2, %p in archive and restore

command strings inserts relative not absolute path of file to process.
This is a side-effect of 2005-07-04 change that makes the server use
relative paths in general.  Noted by Bernd Helmle.

doc/src/sgml/backup.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.92 2006/10/30 00:08:02 neilc Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.93 2006/11/04 18:20:27 tgl Exp $ -->
 
 <chapter id="backup">
  <title>Backup and Restore</title>
@@ -518,8 +518,10 @@ tar -cf backup.tar /usr/local/pgsql/data
     linkend="guc-archive-command"> configuration parameter, which in practice
     will always be placed in the <filename>postgresql.conf</filename> file.
     In this string,
-    any <literal>%p</> is replaced by the absolute path of the file to
+    any <literal>%p</> is replaced by the path name of the file to
     archive, while any <literal>%f</> is replaced by the file name only.
+    (The path name is relative to the working directory of the server,
+    i.e., the cluster's data directory.)
     Write <literal>%%</> if you need to embed an actual <literal>%</>
     character in the command.  The simplest useful command is something
     like
@@ -915,7 +917,9 @@ SELECT pg_stop_backup();
     WAL file segments.  Like the <varname>archive_command</>, this is
     a shell command string.  It may contain <literal>%f</>, which is
     replaced by the name of the desired log file, and <literal>%p</>,
-    which is replaced by the absolute path to copy the log file to.
+    which is replaced by the path name to copy the log file to.
+    (The path name is relative to the working directory of the server,
+    i.e., the cluster's data directory.)
     Write <literal>%%</> if you need to embed an actual <literal>%</>
     character in the command.  The simplest useful command is
     something like
@@ -1003,8 +1007,10 @@ restore_command = 'cp /mnt/server/archivedir/%f %p'
         the WAL file series. This parameter is required.
         Any <literal>%f</> in the string is
         replaced by the name of the file to retrieve from the archive,
-        and any <literal>%p</> is replaced by the absolute path to copy
+        and any <literal>%p</> is replaced by the path name to copy
         it to on the server.
+        (The path name is relative to the working directory of the server,
+        i.e., the cluster's data directory.)
         Write <literal>%%</> to embed an actual <literal>%</> character
         in the command. 
        </para>

doc/src/sgml/config.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.92 2006/10/23 18:10:30 petere Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.93 2006/11/04 18:20:27 tgl Exp $ -->
 
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -1573,9 +1573,11 @@ SET ENABLE_SEQSCAN TO OFF;
         The shell command to execute to archive a completed segment of
         the WAL file series. If this is an empty string (the default),
         WAL archiving is disabled. Any <literal>%p</> in the string is
-        replaced by the absolute path of the file to archive, and any
-        <literal>%f</> is replaced by the file name only. Use
-        <literal>%%</> to embed an actual <literal>%</> character in the
+        replaced by the path name of the file to archive, and any
+        <literal>%f</> is replaced by the file name only.
+        (The path name is relative to the working directory of the server,
+        i.e., the cluster's data directory.)
+        Use <literal>%%</> to embed an actual <literal>%</> character in the
         command. For more information see <xref
         linkend="backup-archiving-wal">.
         This parameter can only be set in the <filename>postgresql.conf</>