linux - 安全退出子进程

Question

我正在尝试学习 fork，这是一个简单的程序:

#!/usr/bin/perl
# PRGNAME.pl by Whom
#
#
use strict;
use warnings;

main(@ARGV);

sub main
{
    my @array = qw(1 2 3 4 5 6);
    while ( (my $t = pop @array) ) {
        if (! (my $pid = fork) ) {
                exit if ( $t == 2 );
                for(;;){}
        }
    }
    waitpid(-1, 0);
    message("This is the $PRGNAME exercise file.");
}

sub message
{
    my $m = shift or return;
    print("$m\n");
}

sub error
{
    my $e = shift || 'unkown error';
    print("$0: $e\n");
    exit 0;
}

但是当我尝试在 shell 上时:ps -fu $LOGNAME | grep [f]ork，我发现:

  i59tib 28361     1   3 16:20:07 pts/34      6:07 /usr/bin/perl ./fork.pl
  i59tib 28363     1   3 16:20:07 pts/34      6:07 /usr/bin/perl ./fork.pl
  i59tib 28366     1   3 16:20:07 pts/34      6:07 /usr/bin/perl ./fork.pl
  i59tib 28364     1   3 16:20:07 pts/34      6:07 /usr/bin/perl ./fork.pl
  i59tib 28362     1   3 16:20:07 pts/34      6:08 /usr/bin/perl ./fork.pl

当我评论这一行时，其中一个进程及其父进程退出了 exit if ( $t == 2 );

然后运行 ​​ps -fu $LOGNAME | grep [f]ork 再次，我发现:

  i59tib   624   623   1 16:29:11 pts/34      0:04 /usr/bin/perl ./fork.pl
  i59tib   629   623   1 16:29:11 pts/34      0:04 /usr/bin/perl ./fork.pl
  i59tib   628   623   1 16:29:11 pts/34      0:04 /usr/bin/perl ./fork.pl
  i59tib   625   623   1 16:29:11 pts/34      0:04 /usr/bin/perl ./fork.pl
  i59tib   627   623   1 16:29:11 pts/34      0:04 /usr/bin/perl ./fork.pl
  i59tib   626   623   1 16:29:11 pts/34      0:04 /usr/bin/perl ./fork.pl
  i59tib   623  4766   0 16:29:11 pts/34      0:00 /usr/bin/perl ./fork.pl

如何在不退出父进程的情况下退出子进程？

Answer 1

How can I exit the child process without exiting the parent?

父级退出是因为父级到达程序末尾，所以告诉父级做某事，任何事情!例如，

1 while waitpid(-1, 0) > 0;