thread2.pl

#!/usr/bin/perl

local $SIG{CHLD} = "IGNORE";

if(!defined($pid = fork())){
	die "无法创建子进程: $!"
}elsif($pid == 0 ){

	print "通过子进程输出: \n";
	exec("date") || die "无法输出日期:$!";
}else{
	print "通过父进程输出\n";
	$ret  = waitpid($pid,0);
	print "完成的进程id: $ret\n"

}