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.

#!/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 Perl. It doesn't provide any benefit over Term::ReadKey, but it shows POSIX termios in action:

# HotKey.pm package 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;

See Also

POSIX Programmer's Guide , by Donald Lewine; O'Reilly & Associates (1991); the documentation for the standard POSIX module, also in Chapter 7 of Programming Perl ; Recipe 15.6 ; Recipe 15.9