<!--
doc/src/sgml/ref/pg_controldata.sgml
PostgreSQL documentation
-->

<refentry id="APP-PGCONTROLDATA">
 <refmeta>
  <refentrytitle><application>pg_controldata</application></refentrytitle>
  <manvolnum>1</manvolnum>
  <refmiscinfo>Application</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>pg_controldata</refname>
  <refpurpose>display control information of a <productname>PostgreSQL</productname> database cluster</refpurpose>
 </refnamediv>

 <indexterm zone="app-pgcontroldata">
  <primary>pg_controldata</primary>
 </indexterm>

 <refsynopsisdiv>
  <cmdsynopsis>
   <command>pg_controldata</command>
   <arg><replaceable class="parameter">datadir</replaceable></arg>
  </cmdsynopsis>
 </refsynopsisdiv>

 <refsect1 id="R1-APP-PGCONTROLDATA-1">
  <title>Description</title>
  <para>
   <command>pg_controldata</command> prints information initialized during
   <command>initdb</>, such as the catalog version.
   It also shows information about write-ahead logging and checkpoint
   processing.  This information is cluster-wide, and not specific to any one
   database.
  </para>

  <para>
   This utility can only be run by the user who initialized the cluster because
   it requires read access to the data directory.
   You can specify the data directory on the command line, or use
   the environment variable <envar>PGDATA</>.  This utility supports the options
   <literal>-V</> and <literal>--version</>, which print the
   <application>pg_controldata</application> version and exit.  It also
   supports options <literal>-?</> and <literal>--help</>, which output the
   supported arguments.
  </para>
 </refsect1>

 <refsect1>
  <title>Environment</title>

  <variablelist>
   <varlistentry>
    <term><envar>PGDATA</envar></term>

    <listitem>
     <para>
      Default data directory location
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>
</refentry>
