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<HTML><HEAD><TITLE>Recipe 15.8. Using POSIX termios (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="1999-07-02T01:43:21Z"><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_08.htm"TITLE="15.7. Ringing the Terminal Bell"><LINKREL="next"HREF="ch15_10.htm"TITLE="15.9. Checking for Waiting Input"></HEAD><BODYBGCOLOR="#FFFFFF"><img alt="Book Home" border="0" src="gifs/smbanner.gif" usemap="#banner-map" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Perl Cookbook"><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><p><TABLEWIDTH="684"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch15_08.htm"TITLE="15.7. Ringing the Terminal Bell"><IMGSRC="../gifs/txtpreva.gif"ALT="Previous: 15.7. Ringing the Terminal Bell"BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="228"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1"><ACLASS="chapter"REL="up"HREF="ch15_01.htm"TITLE="15. User Interfaces"></A></FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch15_10.htm"TITLE="15.9. Checking for Waiting Input"><IMGSRC="../gifs/txtnexta.gif"ALT="Next: 15.9. Checking for Waiting Input"BORDER="0"></A></TD></TR></TABLE></DIV><DIVCLASS="sect1"><H2CLASS="sect1"><ACLASS="title"NAME="ch15-30095">15.8. Using POSIX termios</A></H2><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch15-pgfId-705">Problem<ACLASS="indexterm"NAME="ch15-idx-1000005102-0"></A><ACLASS="indexterm"NAME="ch15-idx-1000005102-1"></A><ACLASS="indexterm"NAME="ch15-idx-1000005102-2"></A><ACLASS="indexterm"NAME="ch15-idx-1000005102-3"></A></A></H3><PCLASS="para">You'd like to manipulate your terminal characteristics directly.</P></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch15-pgfId-711">Solution</A></H3><PCLASS="para">Use the POSIX <CODECLASS="literal">termios</CODE> interface.</P></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch15-pgfId-1000004681">Description</A></H3><PCLASS="para">Think of everything you can do with the <EMCLASS="emphasis">stty</EM> command - you can set everything from special characters to flow control and carriage-return mapping. The standard POSIX module provides direct access to the low-level terminal interface to implement <EMCLASS="emphasis">stty</EM>-like capabilities in your program.</P><PCLASS="para"><ACLASS="xref"HREF="ch15_09.htm#ch15-23903"TITLE="demo POSIX termios">Example 15.2</A> finds what your tty's erase and kill characters are (probably backspace and Ctrl-U). Then it sets them back to their original values out of antiquity, <CODECLASS="literal">#</CODE> and <CODECLASS="literal">@</CODE>, and has you type something. It restores them when done.</P><DIVCLASS="example"><H4CLASS="example"><ACLASS="title"NAME="ch15-23903">Example 15.2: demo POSIX termios</A></H4><PRECLASS="programlisting">#!/usr/bin/perl -w# demo POSIX termiosuse POSIX qw(:termios_h);$term = POSIX::Termios->new;$term->getattr(fileno(STDIN));$erase = $term->getcc(VERASE);$kill = $term->getcc(VKILL);printf "Erase is character %d, %s\n", $erase, uncontrol(chr($erase));printf "Kill is character %d, %s\n", $kill, uncontrol(chr($kill));$term->setcc(VERASE, ord('#'));$term->setcc(VKILL, ord('@'));$term->setattr(1, TCSANOW);print("erase is #, kill is @; type something: ");$line = <STDIN>;print "You typed: $line";$term->setcc(VERASE, $erase);$term->setcc(VKILL, $kill);$term->setattr(1, TCSANOW);sub uncontrol {<ACLASS="indexterm"NAME="ch15-idx-1000005866-0"></A> local $_ = shift; s/([\200-\377])/sprintf("M-%c",ord($1) & 0177)/eg; s/([\0-\37\177])/sprintf("^%c",ord($1) ^ 0100)/eg; return $_;} </PRE></DIV><PCLASS="para">Here's a module called <ACLASS="indexterm"NAME="ch15-idx-1000005113-0"></A>HotKey that implements a <CODECLASS="literal">readkey</CODE> function in pure Perl. It doesn't provide any benefit over Term::ReadKey, but it shows POSIX termios in action:</P><PRECLASS="programlisting"># HotKey.pmpackage HotKey;@ISA = qw(Exporter);@EXPORT = qw(cbreak cooked readkey);use strict;use POSIX qw(:termios_h);my ($term, $oterm, $echo, $noecho, $fd_stdin);$fd_stdin = fileno(STDIN);$term = POSIX::Termios->new();$term->getattr($fd_stdin);$oterm = $term->getlflag();$echo = ECHO | ECHOK | ICANON;$noecho = $oterm & ~$echo;sub cbreak { $term->setlflag($noecho); # ok, so i don't want echo either $term->setcc(VTIME, 1); $term->setattr($fd_stdin, TCSANOW);}sub cooked { $term->setlflag($oterm); $term->setcc(VTIME, 0); $term->setattr($fd_stdin, TCSANOW);}sub readkey { my $key = ''; cbreak(); sysread(STDIN, $key, 1); cooked(); return $key;}END { cooked() }1;<ACLASS="indexterm"NAME="ch15-idx-1000005104-0"></A><ACLASS="indexterm"NAME="ch15-idx-1000005104-1"></A><ACLASS="indexterm"NAME="ch15-idx-1000005104-2"></A></PRE></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch15-pgfId-871">See Also</A></H3><PCLASS="para"><CITECLASS="citetitle">POSIX Programmer's Guide</CITE>, by Donald Lewine; O'Reilly & Associates (1991); the documentation for the standard POSIX 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>; <ACLASS="xref"HREF="ch15_07.htm"TITLE="Reading from the Keyboard">Recipe 15.6</A>; <ACLASS="xref"HREF="ch15_10.htm"TITLE="Checking for Waiting Input">Recipe 15.9</A></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_08.htm"TITLE="15.7. 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