</para>

        <para>
        Unlike most other meta-commands, the entire remainder of the line is
        always taken to be the argument(s) of <command>\!</command>, and neither
        variable interpolation nor backquote expansion are performed in the
        arguments.  The rest of the line is simply passed literally to the
        shell.
        </para>
        </listitem>
      </varlistentry>


      <varlistentry id="app-psql-meta-command-question-mark">
        <term><literal>\? [ <replaceable class="parameter">topic</replaceable> ]</literal></term>
        <listitem>
        <para>
        Shows help information. The optional
        <replaceable class="parameter">topic</replaceable> parameter
        (defaulting to <literal>commands</literal>) selects which part of <application>psql</application> is
        explained: <literal>commands</literal> describes <application>psql</application>'s
        backslash commands; <literal>options</literal> describes the command-line
        options that can be passed to <application>psql</application>;
        and <literal>variables</literal> shows help about <application>psql</application> configuration
        variables.
        </para>
        </listitem>
      </varlistentry>


      <varlistentry id="app-psql-meta-command-semicolon">
        <term><literal>\;</literal></term>
        <listitem>
        <para>
        Backslash-semicolon is not a meta-command in the same way as the
        preceding commands; rather, it simply causes a semicolon to be
        added to the query buffer without any further processing.
        </para>

        <para>
        Normally, <application>psql</application> will dispatch an SQL command to the
        server as soon as it reaches the command-ending semicolon, even if
        more input remains on the current line.  Thus for example entering
<programlisting>
select 1; select 2; select 3;
</programlisting>
        will result in the three SQL commands being individually sent to
        the server, with each one's results being displayed before
        continuing to the next command.  However, a semicolon entered
        as <literal>\;</literal> will not trigger command processing, so that the
        command before it and the one after are effectively combined and
        sent to the server in one request.  So for example
<programlisting>
select 1\; select 2\; select 3;
</programlisting>
        results in sending the three SQL commands to the server in a single
        request, when the non-backslashed semicolon is reached.
        The server executes such a request as a single transaction,
        unless there are explicit <command>BEGIN</command>/<command>COMMIT</command>
        commands included in the string to divide it into multiple
        transactions.  (See <xref linkend="protocol-flow-multi-statement"/>
        for more details about how the server handles multi-query strings.)
        </para>
        </listitem>
      </varlistentry>

    </variablelist>
  </para>

  <refsect3 id="app-psql-patterns" xreflabel="Patterns">
   <title>Patterns</title>

   <indexterm>
    <primary>patterns</primary>
    <secondary>in psql and pg_dump</secondary>
   </indexterm>

  <para>
   The various <literal>\d</literal> commands accept a <replaceable
   class="parameter">pattern</replaceable> parameter to specify the
   object name(s) to be displayed.  In the simplest case, a pattern
   is just the exact name of the object.  The characters within a
   pattern are normally folded to lower case, just as in SQL names;
   for example, <literal>\dt FOO</literal> will display the table named
   <literal>foo</literal>.  As in SQL names, placing double quotes around
   a pattern stops folding to lower case.  Should you need to include
   an actual double quote character in a pattern, write it as a pair
   of double quotes within a double-quote sequence; again this is in
   accord with the rules for SQL quoted identifiers.  For example,
   <literal>\dt