Perl Cookbook

Using POSIX termios

Problem

You’d like to manipulate your terminal characteristics directly.

Solution

Use the POSIX termios interface.

Description

Think of everything you can do with the stty 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 stty-like capabilities in your program.

Example 15.2 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, # and @, and has you type something. It restores them when done.

Example 15-2. demo POSIX termios

#!/usr/bin/perl -w
# demo POSIX termios

use 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 {

    local $_ = shift;
    s/([\200-\377])/sprintf("M-%c",ord($1) & 0177)/eg;
    s/([\0-\37\177])/sprintf("^%c",ord($1) ^ 0100)/eg;
    return $_;
}

Here’s a module called HotKey that implements a readkey function in pure ...