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<span id="Paging-Screen-Output"></span><div class="header">
<p>
Up: <a href="Terminal-Output.html" accesskey="u" rel="up">Terminal Output</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
<span id="Paging-Screen-Output-1"></span><h4 class="subsubsection">14.1.1.1 Paging Screen Output</h4>
<p>When running interactively, Octave normally sends all output directly to the
Command Window. However, when using the CLI version of Octave this can create
a problem because large volumes of data will stream by before you can read
them. In such cases, it is better to use a paging program such as <code>less</code>
or <code>more</code> which displays just one screenful at a time. With <code>less</code>
(and some versions of <code>more</code>) you can also scan forward and backward, and
search for specific items. The pager is enabled by the command <code>more on</code>.
</p>
<p>Normally, no output is displayed by the pager until just before Octave is ready
to print the top level prompt, or read from the standard input (for example, by
using the <code>fscanf</code> or <code>scanf</code> functions). This means that there may
be some delay before any output appears on your screen if you have asked Octave
to perform a significant amount of work with a single command statement. The
function <code>fflush</code> may be used to force output to be sent to the pager (or
any other stream) immediately.
</p>
<p>You can select the program to run as the pager with the <code>PAGER</code> function,
and configure the pager itself with the <code>PAGER_FLAGS</code> function.
</p>
<span id="XREFmore"></span><dl>
<dt id="index-more">: <em></em> <strong>more</strong></dt>
<dt id="index-more-1">: <em></em> <strong>more</strong> <em>on</em></dt>
<dt id="index-more-2">: <em></em> <strong>more</strong> <em>off</em></dt>
<dd><p>Turn output pagination on or off.
</p>
<p>Without an argument, <code>more</code> toggles the current state.
</p>
<p>The current state can be determined via <code>page_screen_output</code>.
</p>
<p><strong>See also:</strong> <a href="#XREFpage_005fscreen_005foutput">page_screen_output</a>, <a href="#XREFpage_005foutput_005fimmediately">page_output_immediately</a>, <a href="#XREFPAGER">PAGER</a>, <a href="#XREFPAGER_005fFLAGS">PAGER_FLAGS</a>.
</p></dd></dl>
<span id="XREFPAGER"></span><dl>
<dt id="index-PAGER">: <em><var>val</var> =</em> <strong>PAGER</strong> <em>()</em></dt>
<dt id="index-PAGER-1">: <em><var>old_val</var> =</em> <strong>PAGER</strong> <em>(<var>new_val</var>)</em></dt>
<dt id="index-PAGER-2">: <em></em> <strong>PAGER</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the program to use
to display terminal output on your system.
</p>
<p>The default value is normally <code>"less"</code>, <code>"more"</code>, or
<code>"pg"</code>, depending on what programs are installed on your system.
See <a href="Installation.html">Installation</a>.
</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="#XREFPAGER_005fFLAGS">PAGER_FLAGS</a>, <a href="#XREFpage_005foutput_005fimmediately">page_output_immediately</a>, <a href="#XREFmore">more</a>, <a href="#XREFpage_005fscreen_005foutput">page_screen_output</a>.
</p></dd></dl>
<span id="XREFPAGER_005fFLAGS"></span><dl>
<dt id="index-PAGER_005fFLAGS">: <em><var>val</var> =</em> <strong>PAGER_FLAGS</strong> <em>()</em></dt>
<dt id="index-PAGER_005fFLAGS-1">: <em><var>old_val</var> =</em> <strong>PAGER_FLAGS</strong> <em>(<var>new_val</var>)</em></dt>
<dt id="index-PAGER_005fFLAGS-2">: <em></em> <strong>PAGER_FLAGS</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that specifies the options to pass
to the pager.
</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="#XREFPAGER">PAGER</a>, <a href="#XREFmore">more</a>, <a href="#XREFpage_005fscreen_005foutput">page_screen_output</a>, <a href="#XREFpage_005foutput_005fimmediately">page_output_immediately</a>.
</p></dd></dl>
<span id="XREFpage_005fscreen_005foutput"></span><dl>
<dt id="index-page_005fscreen_005foutput">: <em><var>val</var> =</em> <strong>page_screen_output</strong> <em>()</em></dt>
<dt id="index-page_005fscreen_005foutput-1">: <em><var>old_val</var> =</em> <strong>page_screen_output</strong> <em>(<var>new_val</var>)</em></dt>
<dt id="index-page_005fscreen_005foutput-2">: <em></em> <strong>page_screen_output</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that controls whether output intended
for the terminal window that is longer than one page is sent through a
pager.
</p>
<p>This allows you to view one screenful at a time. Some pagers
(such as <code>less</code>—see <a href="Installation.html">Installation</a>) are also capable of moving
backward on the output.
</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="#XREFmore">more</a>, <a href="#XREFpage_005foutput_005fimmediately">page_output_immediately</a>, <a href="#XREFPAGER">PAGER</a>, <a href="#XREFPAGER_005fFLAGS">PAGER_FLAGS</a>.
</p></dd></dl>
<span id="XREFpage_005foutput_005fimmediately"></span><dl>
<dt id="index-page_005foutput_005fimmediately">: <em><var>val</var> =</em> <strong>page_output_immediately</strong> <em>()</em></dt>
<dt id="index-page_005foutput_005fimmediately-1">: <em><var>old_val</var> =</em> <strong>page_output_immediately</strong> <em>(<var>new_val</var>)</em></dt>
<dt id="index-page_005foutput_005fimmediately-2">: <em></em> <strong>page_output_immediately</strong> <em>(<var>new_val</var>, "local")</em></dt>
<dd><p>Query or set the internal variable that controls whether Octave sends
output to the pager as soon as it is available.
</p>
<p>When the value is <code>false</code>, Octave buffers its output and waits until just
before the prompt is printed to flush it to the pager. This is the default.
</p>
<p>When <code>page_screen_output</code> is <code>false</code>, this variable has no effect.
</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="#XREFpage_005fscreen_005foutput">page_screen_output</a>, <a href="#XREFmore">more</a>, <a href="#XREFPAGER">PAGER</a>, <a href="#XREFPAGER_005fFLAGS">PAGER_FLAGS</a>.
</p></dd></dl>
<span id="XREFfflush"></span><dl>
<dt id="index-fflush">: <em></em> <strong>fflush</strong> <em>(<var>fid</var>)</em></dt>
<dd><p>Flush output to file descriptor <var>fid</var>.
</p>
<p><code>fflush</code> returns 0 on success and an OS dependent error value
(-1 on Unix) on error.
</p>
<p>Programming Note: Flushing is useful for ensuring that all pending output
makes it to the screen before some other event occurs. For example, it is
always a good idea to flush the standard output stream before calling
<code>input</code>.
</p>
<p><strong>See also:</strong> <a href="Opening-and-Closing-Files.html#XREFfopen">fopen</a>, <a href="Opening-and-Closing-Files.html#XREFfclose">fclose</a>.
</p></dd></dl>
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