<!-- doc/src/sgml/color.sgml -->

<appendix id="color">
 <title>Color Support</title>

 <indexterm zone="color">
  <primary>color</primary>
 </indexterm>

 <para>
  Most programs in the PostgreSQL package can produce colorized console
  output.  This appendix describes how that is configured.
 </para>

 <sect1 id="color-when">
  <title>When Color is Used</title>

  <para>
   To use colorized output, set the environment variable
   <envar>PG_COLOR</envar><indexterm><primary>PG_COLOR</primary></indexterm>
   as follows:

   <orderedlist>
    <listitem>
     <para>
      If the value is <literal>always</literal>, then color is used.
     </para>
    </listitem>

    <listitem>
     <para>
      If the value is <literal>auto</literal> and the standard error stream
      is associated with a terminal device, then color is used.
     </para>
    </listitem>

    <listitem>
     <para>
      Otherwise, color is not used.
     </para>
    </listitem>
   </orderedlist>
  </para>
 </sect1>

 <sect1 id="color-which">
  <title>Configuring the Colors</title>

  <para>
   The actual colors to be used are configured using the environment variable
   <envar>PG_COLORS</envar><indexterm><primary>PG_COLORS</primary></indexterm>
   (note plural).  The value is a colon-separated list of
   <literal><replaceable>key</replaceable>=<replaceable>value</replaceable></literal>
   pairs.  The keys specify what the color is to be used for.  The values are
   SGR (Select Graphic Rendition) specifications, which are interpreted by the
   terminal.
  </para>

  <para>
   The following keys are currently in use:
   <variablelist>
    <varlistentry>
     <term><literal>error</literal></term>
     <listitem>
      <para>used to highlight the text <quote>error</quote> in error messages</para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><literal>warning</literal></term>
     <listitem>
      <para>used to highlight the text <quote>warning</quote> in warning
      messages</para>
     </listitem>
    </varlistentry>

    <varlistentry>
     <term><literal>locus</literal></term>
     <listitem>
      <para>used to highlight location information (e.g., program name and
      file name) in messages</para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>

  <para>
   The default value is <literal>error=01;31:warning=01;35:locus=01</literal>
   (<literal>01;31</literal> = bold red, <literal>01;35</literal> = bold
   magenta, <literal>01</literal> = bold default color).
  </para>

  <tip>
   <para>
    This color specification format is also used by other software packages
    such as <productname>GCC</productname>, <productname>GNU
    coreutils</productname>, and <productname>GNU grep</productname>.
   </para>
  </tip>
 </sect1>
</appendix>
