<!-- doc/src/sgml/basebackup-to-shell.sgml -->

<sect1 id="basebackup-to-shell" xreflabel="basebackup_to_shell">
 <title>basebackup_to_shell &mdash; example "shell" pg_basebackup module</title>

 <indexterm zone="basebackup-to-shell">
  <primary>basebackup_to_shell</primary>
 </indexterm>

 <para>
  <filename>basebackup_to_shell</filename> adds a custom basebackup target
  called <literal>shell</literal>. This makes it possible to run
  <command>pg_basebackup --target=shell</command> or, depending on how this
  module is configured,
  <command>pg_basebackup --target=shell:<replaceable>DETAIL_STRING</replaceable></command>,
  and cause a server command chosen by the server administrator to be executed
  for each tar archive generated by the backup process. The command will receive
  the contents of the archive via standard input.
 </para>

 <para>
  This module is primarily intended as an example of how to create a new
  backup targets via an extension module, but in some scenarios it may be
  useful for its own sake.
  In order to function, this module must be loaded via
  <xref linkend="guc-shared-preload-libraries"/> or
  <xref linkend="guc-local-preload-libraries"/>.
 </para>

 <sect2 id="basebackup-to-shell-configuration-parameters">
  <title>Configuration Parameters</title>

  <variablelist>
   <varlistentry>
    <term>
     <varname>basebackup_to_shell.command</varname> (<type>string</type>)
     <indexterm>
      <primary><varname>basebackup_to_shell.command</varname> configuration parameter</primary>
     </indexterm>
    </term>
    <listitem>
     <para>
      The command which the server should execute for each archive generated
      by the backup process. If <literal>%f</literal> occurs in the command
      string, it will be replaced by the name of the archive (e.g.
      <literal>base.tar</literal>). If <literal>%d</literal> occurs in the
      command string, it will be replaced by the target detail provided by
      the user. A target detail is required if <literal>%d</literal> is
      used in the command string, and prohibited otherwise. For security
      reasons, it may contain only alphanumeric characters. If
      <literal>%%</literal> occurs in the command string, it will be replaced
      by a single <literal>%</literal>. If <literal>%</literal> occurs in
      the command string followed by any other character or at the end of the
      string, an error occurs.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     <varname>basebackup_to_shell.required_role</varname> (<type>string</type>)
     <indexterm>
      <primary><varname>basebackup_to_shell.required_role</varname> configuration parameter</primary>
     </indexterm>
    </term>
    <listitem>
     <para>
      The role required in order to make use of the <literal>shell</literal>
      backup target. If this is not set, any replication user may make use of
      the <literal>shell</literal> backup target.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </sect2>

 <sect2 id="basebackup-to-shell-author">
  <title>Author</title>

  <para>
   Robert Haas <email>rhaas@postgresql.org</email>
  </para>
 </sect2>

</sect1>