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<HTML><HEAD><TITLE>Recipe 15.3. Clearing the Screen (Perl Cookbook)</TITLE><METANAME="DC.title"CONTENT="Perl Cookbook"><METANAME="DC.creator"CONTENT="Tom Christiansen & Nathan Torkington"><METANAME="DC.publisher"CONTENT="O'Reilly & Associates, Inc."><METANAME="DC.date"CONTENT="1999-07-02T01:43:16Z"><METANAME="DC.type"CONTENT="Text.Monograph"><METANAME="DC.format"CONTENT="text/html"SCHEME="MIME"><METANAME="DC.source"CONTENT="1-56592-243-3"SCHEME="ISBN"><METANAME="DC.language"CONTENT="en-US"><METANAME="generator"CONTENT="Jade 1.1/O'Reilly DocBook 3.0 to HTML 4.0"><LINKREV="made"HREF="mailto:online-books@oreilly.com"TITLE="Online Books Comments"><LINKREL="up"HREF="ch15_01.htm"TITLE="15. User Interfaces"><LINKREL="prev"HREF="ch15_03.htm"TITLE="15.2. Testing Whether a Program Is Running Interactively"><LINKREL="next"HREF="ch15_05.htm"TITLE="15.4. 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Determining Terminal or Window Size"><IMGSRC="../gifs/txtnexta.gif"ALT="Next: 15.4. Determining Terminal or Window Size"BORDER="0"></A></TD></TR></TABLE></DIV><DIVCLASS="sect1"><H2CLASS="sect1"><ACLASS="title"NAME="ch15-chap15_clearing_0">15.3. Clearing the Screen</A></H2><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch15-pgfId-325">Problem<ACLASS="indexterm"NAME="ch15-idx-1000005046-0"></A><ACLASS="indexterm"NAME="ch15-idx-1000005046-1"></A><ACLASS="indexterm"NAME="ch15-idx-1000005046-2"></A><ACLASS="indexterm"NAME="ch15-idx-1000005046-3"></A></A></H3><PCLASS="para">You want to clear the screen.</P></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch15-pgfId-331">Solution</A></H3><PCLASS="para">Use the Term::Cap module to send the appropriate character sequence. Use POSIX Termios to get the output speed of the terminal (or guess 9600 bps). Use <CODECLASS="literal">eval</CODE> to trap errors that may arise using POSIX Termios::</P><PRECLASS="programlisting">use Term::Cap;$OSPEED = 9600;eval { require POSIX; my $termios = POSIX::Termios->new(); $termios->getattr; $OSPEED = $termios->getospeed;};$terminal = Term::Cap->Tgetent({OSPEED=>$OSPEED});$terminal->Tputs('cl', 1, STDOUT);</PRE><PCLASS="para">Or, just run the <EMCLASS="emphasis">clear</EM> command:</P><PRECLASS="programlisting">system("clear");</PRE></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch15-pgfId-365">Discussion</A></H3><PCLASS="para">If you clear the screen a lot, cache the return value from the termcap or <EMCLASS="emphasis">clear</EM> command:</P><PRECLASS="programlisting">$clear = $terminal->Tputs('cl');$clear = `clear`;</PRE><PCLASS="para">Then you can clear the screen a hundred times without running <EMCLASS="emphasis">clear</EM> a hundred times:</P><PRECLASS="programlisting">print $clear;</PRE></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch15-pgfId-379">See Also</A></H3><PCLASS="para">Your system's <ICLASS="filename">clear </I>(1) and <ICLASS="filename">termcap </I>(5) manpages (if you have them); the documentation for the standard module Term::Cap module, also in <ACLASS="olink"HREF="../prog/ch07_01.htm">Chapter 7</A> of <ACLASS="citetitle"HREF="../prog/index.htm"TITLE="Programming Perl"><CITECLASS="citetitle">Programming Perl</CITE></A>; the documentation for the Term::Lib module from CPAN</P></DIV></DIV><DIVCLASS="htmlnav"><P></P><HRALIGN="LEFT"WIDTH="684"TITLE="footer"><TABLEWIDTH="684"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch15_03.htm"TITLE="15.2. 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