perl多进程主进程等子进程结束

将“use POSIX ":sys_wait_h";”去掉，还有在主进程中打印子进程中的变量是不对的，主进程不知道子进程的状况，除非你用pipe将变量值传给主进程，
##################################################
#!/usr/bin/perl
#use POSIX ":sys_wait_h";
my $a=10;
for($i=1;$i<=3;$i++){
my $pid=fork();
  if (!defined($pid)) {
        print "Error in fork: $!";
        exit 1;
    }
   if ($pid == 0 ) {
        if($i==1){
        sleep(9);
        $b1=$a+1;
        print "$b1\t";
        exit 0;}
        elsif($i==2){
        sleep(5);
        $b2=$a+10;
        print "$b2\t";
        exit 0;}
        else{
        sleep(3);
        $b3=$a+100;
        print "$b3\t";
        exit 0; }
}
}
print "~~~~~~~~~~split~~~~~~~~~~~\n";
while (($collect = waitpid(-1,WNOHANG)) > 0) {
            1;
}

##################### 输出 ##########
bsd2# perl test.pl
~~~~~~~~~~split~~~~~~~~~~~
110     20      11      bsd2#