<term><option>--char-signedness=<replaceable class="parameter">option</replaceable></option></term>
    <listitem>
     <para>
      Manually set the default char signedness. Possible values are
      <literal>signed</literal> and <literal>unsigned</literal>.
     </para>
     <para>
      For a database cluster that <command>pg_upgrade</command> upgraded from
      a <productname>PostgreSQL</productname> version before 18, the safe
      value would be the default <type>char</type> signedness of the platform
      that ran the cluster before that upgrade. For all other
      clusters, <literal>signed</literal> would be the safe value. However,
      this option is exclusively for use with <command>pg_upgrade</command>
      and should not normally be used manually.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><option>--wal-segsize=<replaceable class="parameter">wal_segment_size</replaceable></option></term>
    <listitem>
     <para>
      Set the new WAL segment size, in megabytes.  The value must be set to a
      power of 2 between 1 and 1024 (megabytes).  See the same option of <xref
      linkend="app-initdb"/> for more information.
     </para>

     <para>
      This option can also be used to change the WAL segment size of an
      existing database cluster, avoiding the need to
      re-<command>initdb</command>.
     </para>

     <note>
      <para>
       While <command>pg_resetwal</command> will set the WAL starting address
       beyond the latest existing WAL segment file, some segment size changes
       can cause previous WAL file names to be reused.  It is recommended to
       use <option>-l</option> together with this option to manually set the
       WAL starting address if WAL file name overlap will cause problems with
       your archiving strategy.
      </para>
     </note>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Environment</title>

  <variablelist>
   <varlistentry>
    <term><envar>PG_COLOR</envar></term>
    <listitem>
     <para>
      Specifies whether to use color in diagnostic messages. Possible values
      are <literal>always</literal>, <literal>auto</literal> and
      <literal>never</literal>.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   This command must not be used when the server is
   running.  <command>pg_resetwal</command> will refuse to start up if
   it finds a server lock file in the data directory.  If the
   server crashed then a lock file might have been left
   behind; in that case you can remove the lock file to allow
   <command>pg_resetwal</command> to run.  But before you do
   so, make doubly certain that there is no server process still alive.
  </para>

  <para>
   <command>pg_resetwal</command> works only with servers of the same
   major version.
  </para>
 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="app-pgcontroldata"/></member>
  </simplelist>
 </refsect1>
</refentry>