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<p>
Next: <a href="Command-Line-Editing.html#Command-Line-Editing" accesskey="n" rel="next">Command Line Editing</a>, Previous: <a href="Quitting-Octave.html#Quitting-Octave" accesskey="p" rel="prev">Quitting Octave</a>, Up: <a href="Getting-Started.html#Getting-Started" accesskey="u" rel="up">Getting Started</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Commands-for-Getting-Help"></a>
<h3 class="section">2.3 Commands for Getting Help</h3>
<a name="index-online-help"></a>
<a name="index-help_002c-online"></a>
<p>The entire text of this manual is available from the Octave prompt
via the command <kbd>doc</kbd>. In addition, the documentation for
individual user-written functions and variables is also available via
the <kbd>help</kbd> command. This section describes the commands used for
reading the manual and the documentation strings for user-supplied
functions and variables. See <a href="Function-Files.html#Function-Files">Function Files</a>, for more information
about how to document the functions you write.
</p>
<a name="XREFhelp"></a><dl>
<dt><a name="index-help"></a>Command: <em></em> <strong>help</strong> <em><var>name</var></em></dt>
<dt><a name="index-help-1"></a>Command: <em></em> <strong>help</strong> <em><code>--list</code></em></dt>
<dt><a name="index-help-2"></a>Command: <em></em> <strong>help</strong> <em><code>.</code></em></dt>
<dd><p>Display the help text for <var>name</var>. For example, the command
<kbd>help help</kbd> prints a short message describing the <code>help</code>
command.
</p>
<p>Given the single argument <code>--list</code>, list all operators,
keywords, built-in functions, and loadable functions available
in the current session of Octave.
</p>
<p>Given the single argument <code>.</code>, list all operators available
in the current session of Octave.
</p>
<p>If invoked without any arguments, <code>help</code> display instructions
on how to access help from the command line.
</p>
<p>The help command can give you information about operators, but not the
comma and semicolons that are used as command separators. To get help
for those, you must type <kbd>help comma</kbd> or <kbd>help semicolon</kbd>.
</p>
<p><strong>See also:</strong> <a href="#XREFdoc">doc</a>, <a href="#XREFlookfor">lookfor</a>, <a href="Status-of-Variables.html#XREFwhich">which</a>.
</p></dd></dl>
<a name="XREFdoc"></a><dl>
<dt><a name="index-doc"></a>Command: <em></em> <strong>doc</strong> <em><var>function_name</var></em></dt>
<dd><p>Display documentation for the function <var>function_name</var>
directly from an online version of
the printed manual, using the GNU Info browser. If invoked without
any arguments, the manual is shown from the beginning.
</p>
<p>For example, the command <kbd>doc rand</kbd> starts the GNU Info browser
at the <code>rand</code> node in the online version of the manual.
</p>
<p>Once the GNU Info browser is running, help for using it is available
using the command <kbd>C-h</kbd>.
</p>
<p><strong>See also:</strong> <a href="#XREFhelp">help</a>.
</p></dd></dl>
<a name="XREFlookfor"></a><dl>
<dt><a name="index-lookfor"></a>Command: <em></em> <strong>lookfor</strong> <em><var>str</var></em></dt>
<dt><a name="index-lookfor-1"></a>Command: <em></em> <strong>lookfor</strong> <em>-all <var>str</var></em></dt>
<dt><a name="index-lookfor-2"></a>Function File: <em>[<var>func</var>, <var>helpstring</var>] =</em> <strong>lookfor</strong> <em>(<var>str</var>)</em></dt>
<dt><a name="index-lookfor-3"></a>Function File: <em>[<var>func</var>, <var>helpstring</var>] =</em> <strong>lookfor</strong> <em>("-all", <var>str</var>)</em></dt>
<dd><p>Search for the string <var>str</var> in all functions found in the current
function search path. By default, <code>lookfor</code> searches for <var>str</var>
in the first sentence of the help string of each function found. The entire
help text of each function can be searched if the <code>"-all"</code> argument is
supplied. All searches are case insensitive.
</p>
<p>Called with no output arguments, <code>lookfor</code> prints the list of
matching functions to the terminal. Otherwise, the output arguments
<var>func</var> and <var>helpstring</var> define the matching functions and the
first sentence of each of their help strings.
</p>
<p>The ability of <code>lookfor</code> to correctly identify the first
sentence of the help text is dependent on the format of the
function’s help. All Octave core functions are correctly
formatted, but the same can not be guaranteed for external packages and
user-supplied functions. Therefore, the use of the <code>"-all"</code>
argument may be necessary to find related functions that are not a part of
Octave.
</p>
<p><strong>See also:</strong> <a href="#XREFhelp">help</a>, <a href="#XREFdoc">doc</a>, <a href="Status-of-Variables.html#XREFwhich">which</a>.
</p></dd></dl>
<p>To see what is new in the current release of Octave, use the <code>news</code>
function.
</p>
<a name="XREFnews"></a><dl>
<dt><a name="index-news"></a>Command: <em></em> <strong>news</strong></dt>
<dt><a name="index-news-1"></a>Command: <em></em> <strong>news</strong> <em><var>package</var></em></dt>
<dd><p>Display the current NEWS file for Octave or an installed package.
</p>
<p>When called without an argument, display the NEWS file for Octave.
When given a package name <var>package</var>, display the current NEWS file for
that package.
</p></dd></dl>
<a name="XREFinfo"></a><dl>
<dt><a name="index-info"></a>Function File: <em></em> <strong>info</strong> <em>()</em></dt>
<dd><p>Display contact information for the GNU Octave community.
</p></dd></dl>
<a name="XREFwarranty"></a><dl>
<dt><a name="index-warranty-1"></a>Built-in Function: <em></em> <strong>warranty</strong> <em>()</em></dt>
<dd><p>Describe the conditions for copying and distributing Octave.
</p></dd></dl>
<p>The following functions can be used to change which programs are used
for displaying the documentation, and where the documentation can be
found.
</p>
<a name="XREFinfo_005ffile"></a><dl>
<dt><a name="index-info_005ffile"></a>Built-in Function: <em><var>val</var> =</em> <strong>info_file</strong> <em>()</em></dt>
<dt><a name="index-info_005ffile-1"></a>Built-in Function: <em><var>old_val</var> =</em> <strong>info_file</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-info_005ffile-2"></a>Built-in Function: <em></em> <strong>info_file</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
Octave info file. The default value is
<samp><var>octave-home</var>/info/octave.info</samp>, in
which <var>octave-home</var> is the root directory of the Octave installation.
The default value may be overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_INFO_FILE</span></code><!-- /@w -->, or the command line argument
‘<samp>--info-file FNAME</samp>’.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFinfo_005fprogram">info_program</a>, <a href="#XREFdoc">doc</a>, <a href="#XREFhelp">help</a>, <a href="#XREFmakeinfo_005fprogram">makeinfo_program</a>.
</p></dd></dl>
<a name="XREFinfo_005fprogram"></a><dl>
<dt><a name="index-info_005fprogram"></a>Built-in Function: <em><var>val</var> =</em> <strong>info_program</strong> <em>()</em></dt>
<dt><a name="index-info_005fprogram-1"></a>Built-in Function: <em><var>old_val</var> =</em> <strong>info_program</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-info_005fprogram-2"></a>Built-in Function: <em></em> <strong>info_program</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
info program to run. The default value is
<samp><var>octave-home</var>/libexec/octave/<var>version</var>/exec/<var>arch</var>/info</samp>
in which <var>octave-home</var> is the root directory of the Octave installation,
<var>version</var> is the Octave version number, and <var>arch</var>
is the system type (for example, <code>i686-pc-linux-gnu</code>). The
default value may be overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_INFO_PROGRAM</span></code><!-- /@w -->, or the command line argument
‘<samp>--info-program NAME</samp>’.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFinfo_005ffile">info_file</a>, <a href="#XREFdoc">doc</a>, <a href="#XREFhelp">help</a>, <a href="#XREFmakeinfo_005fprogram">makeinfo_program</a>.
</p></dd></dl>
<a name="XREFmakeinfo_005fprogram"></a><dl>
<dt><a name="index-makeinfo_005fprogram"></a>Built-in Function: <em><var>val</var> =</em> <strong>makeinfo_program</strong> <em>()</em></dt>
<dt><a name="index-makeinfo_005fprogram-1"></a>Built-in Function: <em><var>old_val</var> =</em> <strong>makeinfo_program</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-makeinfo_005fprogram-2"></a>Built-in Function: <em></em> <strong>makeinfo_program</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
program that Octave runs to format help text containing
Texinfo markup commands. The default value is <code>makeinfo</code>.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFtexi_005fmacros_005ffile">texi_macros_file</a>, <a href="#XREFinfo_005ffile">info_file</a>, <a href="#XREFinfo_005fprogram">info_program</a>, <a href="#XREFdoc">doc</a>, <a href="#XREFhelp">help</a>.
</p></dd></dl>
<a name="XREFtexi_005fmacros_005ffile"></a><dl>
<dt><a name="index-texi_005fmacros_005ffile"></a>Built-in Function: <em><var>val</var> =</em> <strong>texi_macros_file</strong> <em>()</em></dt>
<dt><a name="index-texi_005fmacros_005ffile-1"></a>Built-in Function: <em><var>old_val</var> =</em> <strong>texi_macros_file</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-texi_005fmacros_005ffile-2"></a>Built-in Function: <em></em> <strong>texi_macros_file</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
file containing Texinfo macros that are prepended to documentation strings
before they are passed to makeinfo. The default value is
<samp><var>octave-home</var>/share/octave/<var>version</var>/etc/macros.texi</samp>,
in which <var>octave-home</var> is the root directory of the Octave installation,
and <var>version</var> is the Octave version number.
The default value may be overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_TEXI_MACROS_FILE</span></code><!-- /@w -->, or the command line argument
‘<samp>--texi-macros-file FNAME</samp>’.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFmakeinfo_005fprogram">makeinfo_program</a>.
</p></dd></dl>
<a name="XREFdoc_005fcache_005ffile"></a><dl>
<dt><a name="index-doc_005fcache_005ffile"></a>Built-in Function: <em><var>val</var> =</em> <strong>doc_cache_file</strong> <em>()</em></dt>
<dt><a name="index-doc_005fcache_005ffile-1"></a>Built-in Function: <em><var>old_val</var> =</em> <strong>doc_cache_file</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-doc_005fcache_005ffile-2"></a>Built-in Function: <em></em> <strong>doc_cache_file</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
Octave documentation cache file. A cache file significantly improves
the performance of the <code>lookfor</code> command. The default value is
<samp><var>octave-home</var>/share/octave/<var>version</var>/etc/doc-cache</samp>,
in which <var>octave-home</var> is the root directory of the Octave installation,
and <var>version</var> is the Octave version number.
The default value may be overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_DOC_CACHE_FILE</span></code><!-- /@w -->, or the command line argument
‘<samp>--doc-cache-file FNAME</samp>’.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p>
<p><strong>See also:</strong> <a href="#XREFdoc_005fcache_005fcreate">doc_cache_create</a>, <a href="#XREFlookfor">lookfor</a>, <a href="#XREFinfo_005fprogram">info_program</a>, <a href="#XREFdoc">doc</a>, <a href="#XREFhelp">help</a>, <a href="#XREFmakeinfo_005fprogram">makeinfo_program</a>.
</p></dd></dl>
<a name="XREFbuilt_005fin_005fdocstrings_005ffile"></a><dl>
<dt><a name="index-built_005fin_005fdocstrings_005ffile"></a>Built-in Function: <em><var>val</var> =</em> <strong>built_in_docstrings_file</strong> <em>()</em></dt>
<dt><a name="index-built_005fin_005fdocstrings_005ffile-1"></a>Built-in Function: <em><var>old_val</var> =</em> <strong>built_in_docstrings_file</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-built_005fin_005fdocstrings_005ffile-2"></a>Built-in Function: <em></em> <strong>built_in_docstrings_file</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the name of the
file containing docstrings for built-in Octave functions.
The default value is
<samp><var>octave-home</var>/share/octave/<var>version</var>/etc/built-in-docstrings</samp>,
in which <var>octave-home</var> is the root directory of the Octave installation,
and <var>version</var> is the Octave version number.
The default value may be overridden by the environment variable
<code><span class="nolinebreak">OCTAVE_BUILT_IN_DOCSTRINGS_FILE</span></code><!-- /@w -->, or the command line argument
‘<samp>--built-in-docstrings-file FNAME</samp>’.
</p>
<p>Note: This variable is only used when Octave is initializing itself.
Modifying it during a running session of Octave will have no effect.
</p></dd></dl>
<a name="XREFsuppress_005fverbose_005fhelp_005fmessage"></a><dl>
<dt><a name="index-suppress_005fverbose_005fhelp_005fmessage"></a>Built-in Function: <em><var>val</var> =</em> <strong>suppress_verbose_help_message</strong> <em>()</em></dt>
<dt><a name="index-suppress_005fverbose_005fhelp_005fmessage-1"></a>Built-in Function: <em><var>old_val</var> =</em> <strong>suppress_verbose_help_message</strong> <em>(<var>new_val</var>)</em></dt>
<dt><a name="index-suppress_005fverbose_005fhelp_005fmessage-2"></a>Built-in Function: <em></em> <strong>suppress_verbose_help_message</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that controls whether Octave
will add additional help information to the end of the output from
the <code>help</code> command and usage messages for built-in commands.
</p>
<p>When called from inside a function with the <code>"local"</code> option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
</p></dd></dl>
<p>The following functions are principally used internally by Octave for
generating the documentation. They are documented here for completeness
and because they may occasionally be useful for users.
</p>
<a name="XREFdoc_005fcache_005fcreate"></a><dl>
<dt><a name="index-doc_005fcache_005fcreate"></a>Function File: <em></em> <strong>doc_cache_create</strong> <em>(<var>out_file</var>, <var>directory</var>)</em></dt>
<dd><p>Generate documentation caches for all functions in a given directory.
</p>
<p>A documentation cache is generated for all functions in <var>directory</var>.
The
resulting cache is saved in the file <var>out_file</var>.
The cache is used to speed up <code>lookfor</code>.
</p>
<p>If no directory is given (or it is the empty matrix), a cache for built-in
operators, etc. is generated.
</p>
<p><strong>See also:</strong> <a href="#XREFdoc_005fcache_005ffile">doc_cache_file</a>, <a href="#XREFlookfor">lookfor</a>, <a href="Manipulating-the-Load-Path.html#XREFpath">path</a>.
</p></dd></dl>
<a name="XREFget_005fhelp_005ftext"></a><dl>
<dt><a name="index-get_005fhelp_005ftext"></a>Built-in Function: <em>[<var>text</var>, <var>format</var>] =</em> <strong>get_help_text</strong> <em>(<var>name</var>)</em></dt>
<dd><p>Return the raw help text of function <var>name</var>.
</p>
<p>The raw help text is returned in <var>text</var> and the format in <var>format</var>
The format is a string which is one of <code>"texinfo"</code>,
<code>"html"</code>, or <code>"plain text"</code>.
</p></dd></dl>
<a name="XREFget_005fhelp_005ftext_005ffrom_005ffile"></a><dl>
<dt><a name="index-get_005fhelp_005ftext_005ffrom_005ffile"></a>Built-in Function: <em>[<var>text</var>, <var>format</var>] =</em> <strong>get_help_text_from_file</strong> <em>(<var>fname</var>)</em></dt>
<dd><p>Return the raw help text from the file <var>fname</var>.
</p>
<p>The raw help text is returned in <var>text</var> and the format in <var>format</var>
The format is a string which is one of <code>"texinfo"</code>,
<code>"html"</code>, or <code>"plain text"</code>.
</p></dd></dl>
<a name="XREFget_005ffirst_005fhelp_005fsentence"></a><dl>
<dt><a name="index-get_005ffirst_005fhelp_005fsentence"></a>Function File: <em>[<var>text</var>, <var>status</var>] =</em> <strong>get_first_help_sentence</strong> <em>(<var>name</var>)</em></dt>
<dt><a name="index-get_005ffirst_005fhelp_005fsentence-1"></a>Function File: <em>[<var>text</var>, <var>status</var>] =</em> <strong>get_first_help_sentence</strong> <em>(<var>name</var>, <var>max_len</var>)</em></dt>
<dd><p>Return the first sentence of a function’s help text.
</p>
<p>The first sentence is defined as the text after the function
declaration until either the first period (".") or the first appearance of
two consecutive newlines ("\n\n"). The text is truncated to a maximum
length of <var>max_len</var>, which defaults to 80.
</p>
<p>The optional output argument <var>status</var> returns the status reported by
<code>makeinfo</code>. If only one output argument is requested, and <var>status</var>
is non-zero, a warning is displayed.
</p>
<p>As an example, the first sentence of this help text is
</p>
<div class="example">
<pre class="example">get_first_help_sentence ("get_first_help_sentence")
-| ans = Return the first sentence of a function's help text.
</pre></div>
</dd></dl>
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