identifiers or numbers must be single-quoted. To embed a single
quote in a parameter value, write either two quotes (preferred)
or backslash-quote.
+ If the file contains multiple entries for the same parameter,
+ all but the last one are ignored.
</para>
<para>
</para>
<para>
- In addition to <filename>postgresql.conf</>,
+ In addition to <filename>postgresql.conf</filename>,
a <productname>PostgreSQL</productname> data directory contains a file
- <filename>postgresql.auto.conf</><indexterm><primary>postgresql.auto.conf</></>,
- which has the same format as <filename>postgresql.conf</> but should
- never be edited manually. This file holds settings provided through
- the <xref linkend="SQL-ALTERSYSTEM"> command. This file is automatically
- read whenever <filename>postgresql.conf</> is, and its settings take
- effect in the same way. Settings in <filename>postgresql.auto.conf</>
- override those in <filename>postgresql.conf</>.
+ <filename>postgresql.auto.conf</filename><indexterm><primary>postgresql.auto.conf</primary></indexterm>,
+ which has the same format as <filename>postgresql.conf</filename> but
+ is intended to be edited automatically not manually. This file holds
+ settings provided through the <xref linkend="SQL-ALTERSYSTEM"> command.
+ This file is read whenever <filename>postgresql.conf</filename> is,
+ and its settings take effect in the same way. Settings
+ in <filename>postgresql.auto.conf</filename> override those
+ in <filename>postgresql.conf</filename>.
+ </para>
+
+ <para>
+ External tools may also
+ modify <filename>postgresql.auto.conf</filename>. It is not
+ recommended to do this while the server is running, since a
+ concurrent <command>ALTER SYSTEM</command> command could overwrite
+ such changes. Such tools might simply append new settings to the end,
+ or they might choose to remove duplicate settings and/or comments
+ (as <command>ALTER SYSTEM</command> will).
</para>
<para>
The system view
<link linkend="view-pg-file-settings"><structname>pg_file_settings</structname></link>
- can be helpful for pre-testing changes to the configuration file, or for
- diagnosing problems if a <systemitem>SIGHUP</> signal did not have the
+ can be helpful for pre-testing changes to the configuration files, or for
+ diagnosing problems if a <systemitem>SIGHUP</systemitem> signal did not have the
desired effects.
</para>
</sect2>