files:
<programlisting>
archive_command = 'gzip &lt; %p &gt; /mnt/server/archivedir/%f.gz'
</programlisting>
      You will then need to use <application>gunzip</application> during recovery:
<programlisting>
restore_command = 'gunzip &lt; /mnt/server/archivedir/%f.gz &gt; %p'
</programlisting>
     </para>
    </sect3>

    <sect3 id="backup-scripts">
     <title><varname>archive_command</varname> Scripts</title>

     <para>
      Many people choose to use scripts to define their
      <varname>archive_command</varname>, so that their
      <filename>postgresql.conf</filename> entry looks very simple:
<programlisting>
archive_command = 'local_backup_script.sh "%p" "%f"'
</programlisting>
      Using a separate script file is advisable any time you want to use
      more than a single command in the archiving process.
      This allows all complexity to be managed within the script, which
      can be written in a popular scripting language such as
      <application>bash</application> or <application>perl</application>.
     </para>

     <para>
      Examples of requirements that might be solved within a script include:
      <itemizedlist>
       <listitem>
        <para>
         Copying data to secure off-site data storage
        </para>
       </listitem>
       <listitem>
        <para>
         Batching WAL files so that they are transferred every three hours,
         rather than one at a time
        </para>
       </listitem>
       <listitem>
        <para>
         Interfacing with other backup and recovery software
        </para>
       </listitem>
       <listitem>
        <para>
         Interfacing with monitoring software to report errors
        </para>
       </listitem>
      </itemizedlist>
     </para>

     <tip>
      <para>
       When using an <varname>archive_command</varname> script, it's desirable
       to enable <xref linkend="guc-logging-collector"/>.
       Any messages written to <systemitem>stderr</systemitem> from the script will then
       appear in the database server log, allowing complex configurations to
       be diagnosed easily if they fail.
      </para>
     </tip>
    </sect3>
  </sect2>

  <sect2 id="continuous-archiving-caveats">
   <title>Caveats</title>

   <para>
    At this writing, there are several limitations of the continuous archiving
    technique.  These will probably be fixed in future releases:

  <itemizedlist>
   <listitem>
    <para>