function-reference/query-functions/text.xml


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<?xml version="1.0"?>
<guide self="function-reference/query-functions/">
<chapter>
<title>Query Functions Reference</title>
<body>

<p>
The following functions, which are provided by <c>ebuild.sh</c>, can be used to
query variables and similar state.
</p>

<table>
  <tr>
    <th>
      Function
    </th>
    <th>
      Details
    </th>
  </tr>
  <tr>
    <ti>
      <c>use flagname</c>
    </ti>
    <ti>
      Returns a true value if and only if <c>flagname</c> is enabled.
      The condition is inverted if prefixed with an exclamation mark,
      <c>!flagname</c>.
      It is guaranteed that <c>use</c> produces no output.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>useq flagname</c>
    </ti>
    <ti>
      Deprecated synonym for <c>use</c>.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>usev flagname</c>
    </ti>
    <ti>
      As <c>use</c>, echoes <c>flagname</c> upon success.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>use_enable flag str val</c> 
    </ti>
    <ti>
      Echoes either <c>--enable-str=val</c> or <c>--disable-str</c> depending upon <c>useq flag</c>.
      If <c>str</c> is not specified, uses <c>flag</c> instead. If <c>val</c> is not specified, omits
      the assignment part.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>use_with flag str val</c>
    </ti>
    <ti>
      As <c>use_enable</c>, but <c>--with-</c> or <c>--without-</c>.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>has flag string</c>
    </ti>
    <ti>
      Returns true if <c>flag</c> is included in the flag list <c>string</c>
      (example: <c>if has ccache $FEATURES ; then</c>).
      The condition is inverted if prefixed with an exclamation mark,
      <c>!flag</c>.
      It is guaranteed that <c>has</c> produces no output.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>hasq flag string</c>
    </ti>
    <ti>
      Deprecated synonym for <c>has</c>.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>hasv flag string</c>
    </ti>
    <ti>
      As <c>has</c>, echoes <c>flag</c> on success.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>best_version pkg</c>
    </ti>
    <ti>
      Echoes category, name and version of the highest version of <c>pkg</c>
      that is currently installed.
      Example: <c>best_version app-editors/emacs:24</c> will output
      <c>app-editors/emacs-24.5-r3</c>.
    </ti>
  </tr>
  <tr>
    <ti>
      <c>has_version pkg[flag]</c>
    </ti>
    <ti>
      True if <c>pkg</c> (can include
      <uri link="::general-concepts/dependencies#version specifiers"/>
      and
      <uri link="::general-concepts/dependencies#built with use dependencies"/>)
      is installed. Example: <c>has_version
      "=app-editors/nano-2.5.3[nls,spell]"</c>.
    </ti>
  </tr>
</table>

</body>
</chapter>
</guide>