Fix missed use of "cp -i" in an example, per Fujii Masao.

Also be more careful about markup: use & not just &.

doc/src/sgml/backup.sgml

@@ -579,7 +579,7 @@ tar -cf backup.tar /usr/local/pgsql/data
     character in the command.  The simplest useful command is something
     like:
 <programlisting>
-archive_command = 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f'  # Unix
+archive_command = 'test ! -f /mnt/server/archivedir/%f &amp;&amp; cp %p /mnt/server/archivedir/%f'  # Unix
 archive_command = 'copy "%p" "C:\\server\\archivedir\\%f"'  # Windows
 </programlisting>
     which will copy archivable WAL segments to the directory
@@ -1213,7 +1213,7 @@ restore_command = 'cp /mnt/server/archivedir/%f %p'
       <literal>on</>, and set up an <varname>archive_command</> that performs
       archiving only when a <emphasis>switch file</> exists.  For example:
 <programlisting>
-archive_command = 'test ! -f /var/lib/pgsql/backup_in_progress || cp -i %p /var/lib/pgsql/archive/%f &lt; /dev/null'
+archive_command = 'test ! -f /var/lib/pgsql/backup_in_progress || (test ! -f /var/lib/pgsql/archive/%f &amp;&amp; cp %p /var/lib/pgsql/archive/%f)'
 </programlisting>
       This command will perform archiving when
       <filename>/var/lib/pgsql/backup_in_progress</> exists, and otherwise