15.7.1. Problem You want to sound an alarm on the user's terminal.

15.7.2. Solution
Print the "\a" character to sound a bell: 

print "\aWake up!\n";
Or use the "vb" terminal capability to show a visual bell:

use Term::Cap;

$OSPEED = 9600;
eval {
    require POSIX;
    my $termios = POSIX::Termios->new( );
    $termios->getattr;
    $OSPEED = $termios->getospeed;
};

$terminal = Term::Cap->Tgetent({OSPEED=>$OSPEED});
$vb = "";
eval {
    $terminal->Trequire("vb");
    $vb = $terminal->Tputs('vb', 1);
};

print $vb;                                  # ring visual bell
15.7.3. Discussion
The "\a" escape is the same as "\cG", "\007", and "\x07". They all cor
+respond to the ASCII BEL character and cause an irritating ding. In a
+ crowded terminal room at the end of the semester, this beeping cause
+d by dozens of vi novices all trying to get out of insert mode at onc
+e can be maddening. The visual bell is a workaround to avoid irritati
+on. Based upon the polite principle that terminals should be seen and
+ not heard (at least, not in crowded rooms), some terminals let you b
+riefly reverse the foreground and background colors to give a flash o
+f light instead of an audible ring.

Not every terminal supports the visual bell, which is why we eval the 
+code that finds it. If the terminal doesn't support it, Trequire will
+ die without having changed the value of $vb from "". If the terminal
+ does support it, the value of $vb will be set to the character seque
+nce to flash the bell.

There's a better approach to the bell issue in graphical terminal syst
+ems like xterm. Many of these let you enable the visual bell from the
+ enclosing application itself, allowing all programs that blindly out
+put a chr(7) to become less noisy.
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