[Perl] $SIG{HUP}

Scenarios: 爲daemon process重新加載配置
Solution: 可通過接收SIGHUP，並定義操作。如下實現了向 a daemon process 發送SIGHUP，並restart該process。當然，也可以是加載配置。

#!/usr/bin/perl
use strict;
use warnings;
use POSIX ();
use FindBin ();
use File::Basename ();
use File::Spec::Functions qw(catfile);

$| = 1;
# make the daemon cross-platform, so exec always calls the script
# itself with the right path, no matter how the script was invoked.
my $script = File::Basename::basename($0);
my $SELF  = catfile($FindBin::Bin, $script);
# POSIX unmasks the sigprocmask properly
$SIG{HUP} = sub {
    print "got SIGHUP\n";
    exec($SELF, @ARGV) || die "$0: couldn't restart: $!";
};

code();

sub code {
    print "PID: $$\n";
    print "ARGV: @ARGV\n";
    my $count = 0;
    while (1) {
        sleep 2;
        print ++$count, "\n";
}

Start a pty on your host, and run below daemon program:

[root@localhost tmp]# perl test_sighup.pl
PID: 27460
ARGV: 
1

Then start another pty, and send SIGHUP:

[root@localhost ~]# kill -1 27460

Back to the former pty, will see:

[root@localhost tmp]# perl test_sighup.pl
PID: 27460
ARGV: 
1
2
3
got SIGHUP

See also

SIGINT
SIGALRM
SIGCHLD