order for
         the line editing features of <application>Readline</application> to work properly, these
         non-printing control characters must be designated as invisible
         by surrounding them with <literal>%[</literal> and
         <literal>%]</literal>. Multiple pairs of these can occur within
         the prompt.  For example:
<programlisting>
testdb=&gt; \set PROMPT1 '%[%033[1;33;40m%]%n@%/%R%[%033[0m%]%# '
</programlisting>
         results in a boldfaced (<literal>1;</literal>) yellow-on-black
         (<literal>33;40</literal>) prompt on VT100-compatible, color-capable
         terminals.
        </para>
        </listitem>
      </varlistentry>

      <varlistentry id="app-psql-prompting-w">
        <term><literal>%w</literal></term>
        <listitem>
        <para>
        Whitespace of the same width as the most recent output of
        <varname>PROMPT1</varname>.  This can be used as a
        <varname>PROMPT2</varname> setting, so that multi-line statements are
        aligned with the first line, but there is no visible secondary prompt.
        </para>
        </listitem>
      </varlistentry>

    </variablelist>

    To insert a percent sign into your prompt, write
    <literal>%%</literal>. The default prompts are
    <literal>'%/%R%x%# '</literal> for prompts 1 and 2, and
    <literal>'&gt;&gt; '</literal> for prompt 3.
    </para>

    <note>
    <para>
    This feature was shamelessly plagiarized from
    <application>tcsh</application>.
    </para>
    </note>

   </refsect3>

   <refsect3 id="app-psql-readline">
    <title>Command-Line Editing</title>

   <indexterm>
    <primary>Readline</primary>
    <secondary>in psql</secondary>
   </indexterm>
   <indexterm>
    <primary>libedit</primary>
    <secondary>in psql</secondary>
   </indexterm>

    <para>
    <application>psql</application> uses
    the <application>Readline</application>
    or <application>libedit</application> library, if available, for
    convenient line editing and retrieval.  The command history is
    automatically saved when <application>psql</application> exits and is
    reloaded when <application>psql</application> starts up.  Type
    up-arrow or control-P to retrieve previous lines.
    </para>

    <para>
    You can also use tab completion to fill in partially-typed keywords
    and SQL object names in many (by no means all) contexts.  For example,
    at the start of a command, typing <literal>ins</literal> and pressing
    TAB will fill in <literal>insert into </literal>.  Then, typing a few
    characters of a table or schema name and pressing <literal>TAB</literal>
    will fill in the unfinished name, or offer a menu of possible completions
    when there's more than one.  (Depending on the library in use, you may need to
    press <literal>TAB</literal> more than once to get a menu.)
    </para>

    <para>
    Tab completion for SQL object names requires sending queries to the
    server to find possible matches.  In some contexts this can interfere
    with other operations.  For example, after <command>BEGIN</command>
    it will be too late to issue <command>SET TRANSACTION ISOLATION
    LEVEL</command> if a tab-completion query is issued in between.
    If you do not want tab completion at all, you
    can turn it off permanently by putting this in a file named
    <filename>.inputrc</filename> in your home directory:
<programlisting>
$if psql
set disable-completion on
$endif
</programlisting>
    (This is not a <application>psql</application> but a
    <application>Readline</application> feature. Read its documentation
    for further details.)
    </para>

    <para>
     The <option>-n</option> (<option>--no-readline</option>) command line
     option can also be useful to disable use
     of <application>Readline</application> for a single run
     of <application>psql</application>.  This prevents tab completion,
     use or recording of command line history, and editing of multi-line