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doc/src/sgml/ref/pg_ctl-ref.sgml
PostgreSQL documentation
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<refentry id="app-pg-ctl">
 <refmeta>
  <refentrytitle><application>pg_ctl</application></refentrytitle>
  <manvolnum>1</manvolnum>
  <refmiscinfo>Application</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>pg_ctl</refname>
  <refpurpose>initialize, start, stop, or restart a <productname>PostgreSQL</productname> server</refpurpose>
 </refnamediv>

 <indexterm zone="app-pg-ctl">
  <primary>pg_ctl</primary>
 </indexterm>

 <refsynopsisdiv>
  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">init[db]</arg>
   <arg>-s</arg>
   <arg>-D <replaceable>datadir</replaceable></arg>
   <arg>-o <replaceable>initdb-options</replaceable></arg>
  </cmdsynopsis>

  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">start</arg>
   <arg>-w</arg>
   <arg>-t <replaceable>seconds</replaceable></arg>
   <arg>-s</arg>
   <arg>-D <replaceable>datadir</replaceable></arg>
   <arg>-l <replaceable>filename</replaceable></arg>
   <arg>-o <replaceable>options</replaceable></arg>
   <arg>-p <replaceable>path</replaceable></arg>
   <arg>-c</arg>
  </cmdsynopsis>

  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">stop</arg>
   <arg>-W</arg>
   <arg>-t <replaceable>seconds</replaceable></arg>
   <arg>-s</arg>
   <arg>-D <replaceable>datadir</replaceable></arg>
   <arg>-m
     <group choice="plain">
       <arg>s[mart]</arg>
       <arg>f[ast]</arg>
       <arg>i[mmediate]</arg>
     </group>
   </arg>
  </cmdsynopsis>

  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">restart</arg>
   <arg>-w</arg>
   <arg>-t <replaceable>seconds</replaceable></arg>
   <arg>-s</arg>
   <arg>-D <replaceable>datadir</replaceable></arg>
   <arg>-c</arg>
   <arg>-m
     <group choice="plain">
       <arg>s[mart]</arg>
       <arg>f[ast]</arg>
       <arg>i[mmediate]</arg>
     </group>
   </arg>
   <arg>-o <replaceable>options</replaceable></arg>
  </cmdsynopsis>

  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">reload</arg>
   <arg>-s</arg>
   <arg>-D <replaceable>datadir</replaceable></arg>
  </cmdsynopsis>

  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">status</arg>
   <arg>-D <replaceable>datadir</replaceable></arg>
  </cmdsynopsis>

  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">kill</arg>
   <arg><replaceable>signal_name</replaceable></arg>
   <arg><replaceable>process_id</replaceable></arg>
  </cmdsynopsis>

  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">register</arg>
   <arg>-N <replaceable>servicename</replaceable></arg>
   <arg>-U <replaceable>username</replaceable></arg>
   <arg>-P <replaceable>password</replaceable></arg>
   <arg>-D <replaceable>datadir</replaceable></arg>
   <arg>-S
     <group choice="plain">
       <arg>a[uto]</arg>
       <arg>d[emand]</arg>
     </group>
   </arg>
   <arg>-w</arg>
   <arg>-t <replaceable>seconds</replaceable></arg>
   <arg>-o <replaceable>options</replaceable></arg>
  </cmdsynopsis>

  <cmdsynopsis>
   <command>pg_ctl</command>
   <arg choice="plain">unregister</arg>
   <arg>-N <replaceable>servicename</replaceable></arg>
  </cmdsynopsis>
 </refsynopsisdiv>


 <refsect1 id="app-pg-ctl-description">
  <title>Description</title>
  <para>
   <application>pg_ctl</application> is a utility for initializing a
   <productname>PostgreSQL</productname> database cluster, starting,
   stopping, or restarting the <productname>PostgreSQL</productname>
   backend server (<xref linkend="app-postgres">), or displaying the
   status of a running server.  Although the server can be started
   manually, <application>pg_ctl</application> encapsulates tasks such
   as redirecting log output and properly detaching from the terminal
   and process group. It also provides convenient options for
   controlled shutdown.
  </para>

  <para>
   The <option>init</option> or <option>initdb</option> mode creates a new
   <productname>PostgreSQL</productname> database cluster.  A database
   cluster is a collection of databases that are managed by a single
   server instance.  This mode invokes the <command>initdb</command>
   command.  See <xref linkend="app-initdb"> for details.
  </para>

  <para>
   In <option>start</option> mode, a new server is launched.  The
   server is started in the background, and its standard input is attached
   to <filename>/dev/null</filename> (or <literal>nul</> on Windows).
   On Unix-like systems, by default, the server's standard output and
   standard error are sent to <application>pg_ctl</application>'s
   standard output (not standard error).  The standard output of
   <application>pg_ctl</application> should then be redirected to a
   file or piped to another process such as a log rotating program
   like <application>rotatelogs</>; otherwise <command>postgres</command>
   will write its output to the controlling terminal (from the
   background) and will not leave the shell's process group.  On
   Windows, by default the server's standard output and standard error
   are sent to the terminal.  These default behaviors can be changed
   by using <option>-l</option> to append the server's output to a log file.
   Use of either <option>-l</option> or output redirection is recommended.
  </para>

  <para>
   In <option>stop</option> mode, the server that is running in
   the specified data directory is shut down.  Three different
   shutdown methods can be selected with the <option>-m</option>
   option.  <quote>Smart</quote> mode (the default) waits for all active
   clients to disconnect and any online backup to finish.
   If the server is in hot standby, recovery and streaming replication
   will be terminated once all clients have disconnected.
   <quote>Fast</quote> mode does not wait for clients to disconnect and
   will terminate an online backup in progress.  All active transactions are
   rolled back and clients are forcibly disconnected, then the
   server is shut down.  <quote>Immediate</quote> mode will abort
   all server processes immediately, without a clean shutdown.
   This will lead to a crash-recovery run on the next restart.
  </para>

  <para>
   <option>restart</option> mode effectively executes a stop followed
   by a start.  This allows changing the <command>postgres</command>
   command-line options.
  </para>

  <para>
   <option>reload</option> mode simply sends the
   <command>postgres</command> process a <systemitem>SIGHUP</>
   signal, causing it to reread its configuration files
   (<filename>postgresql.conf</filename>,
   <filename>pg_hba.conf</filename>, etc.).  This allows changing of
   configuration-file options that do not require a complete restart
   to take effect.
  </para>

  <para>
   <option>status</option> mode checks whether a server is running in
   the specified data directory. If it is, the <acronym>PID</acronym>
   and the command line options that were used to invoke it are
   displayed.
  </para>

  <para>
   <option>kill</option> mode allows you to send a signal to a specified
    process.  This is particularly valuable for <productname>Microsoft Windows</>
    which does not have a <application>kill</> command.  Use
    <literal>--help</> to see a list of supported signal names.
  </para>

  <para>
   <option>register</option> mode allows you to register a system service
   on <productname>Microsoft Windows</>.  The <option>-S</option> option
   allows selection of service start type, either <quote>auto</quote> (start
   service automatically on system startup) or <quote>demand</quote> (start
   service on demand).
  </para>

  <para>
   <option>unregister</option> mode allows you to unregister a system service
   on <productname>Microsoft Windows</>.  This undoes the effects of the
   <option>register</option> command.
  </para>
 </refsect1>

 <refsect1 id="app-pg-ctl-options">
  <title>Options</title>

    <variablelist>

     <varlistentry>
      <term><option>-c</option></term>
      <listitem>
       <para>
        Attempt to allow server crashes to produce core files, on platforms
        where this is possible, by lifting any soft resource limit placed on
        core files.
        This is useful in debugging or diagnosing problems by allowing a
        stack trace to be obtained from a failed server process.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-D <replaceable class="parameter">datadir</replaceable></option></term>
      <listitem>
       <para>
        Specifies the file system location of the database files.  If
        this is omitted, the environment variable
        <envar>PGDATA</envar> is used.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-l <replaceable class="parameter">filename</replaceable></option></term>
      <listitem>
       <para>
        Append the server log output to
        <replaceable>filename</replaceable>.  If the file does not
        exist, it is created.  The <systemitem>umask</> is set to 077,
        so access to the log file is disallowed to other users by default.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-m <replaceable class="parameter">mode</replaceable></option></term>
      <listitem>
       <para>
        Specifies the shutdown mode.  <replaceable>mode</replaceable>
        can be <literal>smart</literal>, <literal>fast</literal>, or
        <literal>immediate</literal>, or the first letter of one of
        these three.  If this is omitted, <literal>smart</literal> is used.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-o <replaceable class="parameter">options</replaceable></option></term>
      <listitem>
       <para>
        Specifies options to be passed directly to the
        <command>postgres</command> command.
       </para>
       <para>
        The options should usually be surrounded by single or double
        quotes to ensure that they are passed through as a group.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-o <replaceable class="parameter">initdb-options</replaceable></option></term>
      <listitem>
       <para>
        Specifies options to be passed directly to the
        <command>initdb</command> command.
       </para>
       <para>
        The options should usually be surrounded by single or double
        quotes to ensure that they are passed through as a group.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-p <replaceable class="parameter">path</replaceable></option></term>
      <listitem>
       <para>
        Specifies the location of the <filename>postgres</filename>
        executable.  By default the <filename>postgres</filename> executable is taken from the same
        directory as <command>pg_ctl</command>, or failing that, the hard-wired
        installation directory.  It is not necessary to use this
        option unless you are doing something unusual and get errors
        that the <filename>postgres</filename> executable was not found.
       </para>

       <para>
        In <literal>init</literal> mode, this option analogously
        specifies the location of the <filename>initdb</filename>
        executable.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-s</option></term>
      <listitem>
       <para>
        Print only errors, no informational messages.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-t</option></term>
      <listitem>
       <para>
        The maximum number of seconds to wait when waiting for startup or
        shutdown to complete.  The default is 60 seconds.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-w</option></term>
      <listitem>
       <para>
        Wait for the startup or shutdown to complete.
        Waiting is the default option for shutdowns, but not startups.
        When waiting for startup, <command>pg_ctl</command> repeatedly
        attempts to connect to the server.
        When waiting for shutdown, <command>pg_ctl</command> waits for
        the server to remove its <acronym>PID</acronym> file.
        <command>pg_ctl</command> returns an exit code based on the
        success of the startup or shutdown.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><option>-W</option></term>
      <listitem>
       <para>
        Do not wait for startup or shutdown to complete.  This is the
        default for start and restart modes.
       </para>
      </listitem>
     </varlistentry>
   </variablelist>

  <refsect2 id="app-pg-ctl-windows-options">
   <title>Options for Windows</title>

   <variablelist>
    <varlistentry>
     <term><option>-N <replaceable class="parameter">servicename</replaceable></option></term>
     <listitem>
      <para>
       Name of the system service to register. The name will be used
       as both the service name and the display name.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><option>-U <replaceable class="parameter">username</replaceable></option></term>
     <listitem>
      <para>
       User name for the user to start the service. For domain users, use the
       format <literal>DOMAIN\username</literal>.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><option>-P <replaceable class="parameter">password</replaceable></option></term>
     <listitem>
      <para>
       Password for the user to start the service.
      </para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><option>-S <replaceable class="parameter">start-type</replaceable></option></term>
     <listitem>
      <para>
       Start type of the system service to register.  start-type can
       be <literal>auto</literal>, or <literal>demand</literal>, or
       the first letter of one of these two. If this is omitted,
       <literal>auto</literal> is used.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </refsect2>

 </refsect1>


 <refsect1>
  <title>Environment</title>

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

    <listitem>
     <para>
      Default data directory location.
     </para>
    </listitem>
   </varlistentry>

  </variablelist>

  <para>
   <command>pg_ctl</command>, like most other <productname>PostgreSQL</>
   utilities,
   also uses the environment variables supported by <application>libpq</>
   (see <xref linkend="libpq-envars">).
   For additional server variables, see <xref linkend="app-postgres">.
  </para>
 </refsect1>


 <refsect1>
  <title>Files</title>

  <variablelist>
   <varlistentry>
    <term><filename>postmaster.pid</filename></term>

    <listitem>
     <para>
      The existence of this file in the data directory is used to help
      <application>pg_ctl</application> determine if the server is
      currently running.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><filename>postmaster.opts</filename></term>

    <listitem>
     <para>If this file exists in the data directory,
      <application>pg_ctl</application> (in <option>restart</option> mode)
      will pass the contents of the file as options to
      <application>postgres</application>, unless overridden
      by the <option>-o</option> option. The contents of this file
      are also displayed in <option>status</option> mode.
     </para>
    </listitem>
   </varlistentry>

  </variablelist>
 </refsect1>


 <refsect1 id="R1-APP-PGCTL-2">
  <title>Examples</title>

  <refsect2 id="R2-APP-PGCTL-3">
   <title>Starting the Server</title>

   <para>
    To start up a server:
<screen>
<prompt>$</prompt> <userinput>pg_ctl start</userinput>
</screen>
   </para>

   <para>
    An example of starting the server, and waiting until the server is
    accepting connection:
<screen>
<prompt>$</prompt> <userinput>pg_ctl -w start</userinput>
</screen>
   </para>

   <para>
    For a server using port 5433, and
    running without <function>fsync</function>, use:
<screen>
<prompt>$</prompt> <userinput>pg_ctl -o "-F -p 5433" start</userinput>
</screen>
   </para>
  </refsect2>

  <refsect2 id="R2-APP-PGCTL-4">
   <title>Stopping the Server</title>
   <para>
    To stop the server, use:
<screen>
<prompt>$</prompt> <userinput>pg_ctl stop</userinput>
</screen>
    The <option>-m</option> option allows control over
    <emphasis>how</emphasis> the server shuts down.
   </para>
  </refsect2>

  <refsect2 id="R2-APP-PGCTL-5">
   <title>Restarting the Server</title>

   <para>
    Restarting the server is almost equivalent to stopping the
    server and starting it again,
    except that <command>pg_ctl</command> saves and reuses the command line options that
    were passed to the previously running instance.  To restart
    the server in the simplest form, use:
<screen>
<prompt>$</prompt> <userinput>pg_ctl restart</userinput>
</screen>
   </para>

   <para>
    To restart the server,
    waiting for it to shut down and restart:
<screen>
<prompt>$</prompt> <userinput>pg_ctl -w restart</userinput>
</screen>
   </para>

   <para>
    To restart using port 5433 and disable <function>fsync</> upon restart:
<screen>
<prompt>$</prompt> <userinput>pg_ctl -o "-F -p 5433" restart</userinput>
</screen>
   </para>
  </refsect2>

  <refsect2 id="R2-APP-PGCTL-6">
   <title>Showing the Server Status</title>

   <para>
    Here is sample status output from
    <application>pg_ctl</application>:
<screen>
<prompt>$</prompt> <userinput>pg_ctl status</userinput>
<computeroutput>
pg_ctl: server is running (PID: 13718)
/usr/local/pgsql/bin/postgres "-D" "/usr/local/pgsql/data" "-p" "5433" "-B" "128"
</computeroutput>
</screen>
    This is the command line that would be invoked in restart mode.
   </para>
  </refsect2>
 </refsect1>


 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="app-initdb"></member>
   <member><xref linkend="app-postgres"></member>
  </simplelist>
 </refsect1>

</refentry>
