Perl's special variables are documented in perlvar: %SIG

Thank you but this is only give few examples. I am looking for a document explains all the signals' meaning and trigger.

I am looking for a document explains all the signals' meaning and trigger.

The signals special to Perl, like __WARN__ and __DIE__, are documented in %SIG, the other signals are generally POSIX signals, which you can read about for example in signal(7) like here and here, or in Signal (IPC). Note that a lot of signals may be OS-specific. If you could tell us what you want to use them for (and on which platforms), perhaps we can give more specific advice.

https://perldoc.perl.org/perlipc#Signals

signals on windows are well summariazed here.

As far as I remember and also glancing the above module comment INT,QUIT,BREAK are handled in windows so you can use BREAK to do something else than die, I must have written some program using that signal to partially report a long running job status.

See also Catch-and-Handle-Signals-in-Perl by David Farrel (not windows specific tho).

Then Signals vs. Windows SIGHUP delivered on Windows Strawberry Perl and alarm() on Windows and sending signal to self with kill on windows. Recently I used $SIG{INT} and also some link in my Bibliotheca

A simple example to start: I run this infinite loop and pressed 3 times CTRL-BREAK and then CTRL-C to terminate it.

use strict;
use warnings;

my $growing_number;

# Handle Ctrl-C
$SIG{INT} = sub{ 
    print "INT: last value of \$growing_number is: $growing_number\nTe
+rminating..\n";
    exit;
};

# Handle Ctrl-Break
$SIG{BREAK} = sub{ 
    print "BREAK: Currently \$growing_number is: $growing_number\n";
};


while (1){
    $growing_number += time;
    sleep 1;
}

__END__
BREAK: Currently $growing_number is: 10049615223
BREAK: Currently $growing_number is: 18424294603
BREAK: Currently $growing_number is: 23449102243
INT: last value of $growing_number is: 28473909892
Terminating..
[download]

L*

PS note also that if you put sleep 60 then the OS in question catch the signal every 60 seconds.. not so good. You can workaround it using sleep 1 for 1..60

Since you seem to be asking a fairly general question about signals, I would advise you to avoid them as much as you possibly can, especially on Windows.

As for why, this long discussion thread includes a lot of historical detail on the personalities and politics behind early Windows development, especially signals and the Windows POSIX subsystem.

Update: to further clarify, signals should be avoided on Windows, where they are not a native IPC mechanism. Though there is no avoiding them on Unix (where they are native) you must take great care when writing C signal handlers to ensure they are async-signal-safe because they tend to crash and malfunction in strange ways if not (as noted here recently :). Disclaimer: though I've used signals in Unix C code, I've hardly used them in Perl. You might like to search for "signal" in this long technical node from the inimitable BrowserUk describing his experiences with signals on Windows, where he noted "their use in multi-threaded Perl code is very confused".