如何重新初始化 Perl 的 STDIN/STDOUT/STDERR? [英] How can I reinitialize Perl's STDIN/STDOUT/STDERR?

问题描述

我有一个 Perl 脚本，它可以对自身进行分叉和守护进程.它由 cron 运行，所以为了不留下僵尸，我关闭了 STDIN、STDOUT 和 STDERR:

I have a Perl script which forks and daemonizes itself. It's run by cron, so in order to not leave a zombie around, I shut down STDIN,STDOUT, and STDERR:

open STDIN, '/dev/null'   or die "Can't read /dev/null: $!";
open STDOUT, '>>/dev/null' or die "Can't write to /dev/null: $!";
open STDERR, '>>/dev/null' or die "Can't write to /dev/null: $!";
if (!fork()) {
  do_some_fork_stuff();
  }

我的问题是:我想在此之后至少恢复 STDOUT(恢复其他 2 个会很好).但是我需要使用什么魔法符号来重新打开 STDOUT 就像以前的 STDOUT 一样?

The question I have is: I'd like to restore at least STDOUT after this point (it would be nice to restore the other 2). But what magic symbols do I need to use to re-open STDOUT as what STDOUT used to be?

我知道如果我从 tty 运行，我可以使用/dev/tty"(但我从 cron 运行并且依赖于其他地方的 stdout).我还阅读了一些技巧，您可以通过 open SAVEOUT,">&STDOUT" 将 STDOUT 放在一边，但只是制作此副本的行为并不能解决留下僵尸的原始问题.

I know that I could use "/dev/tty" if I was running from a tty (but I'm running from cron and depending on stdout elsewhere). I've also read tricks where you can put STDOUT aside with open SAVEOUT,">&STDOUT", but just the act of making this copy doesn't solve the original problem of leaving a zombie around.

我想看看是否有一些魔法，比如 open STDOUT,"|-"(我知道不是这样)以它应该打开的方式打开 STDOUT.p>

I'm looking to see if there's some magic like open STDOUT,"|-" (which I know isn't it) to open STDOUT the way it's supposed to be opened.

推荐答案

如果它仍然有用，我会想到两件事:

If it's still useful, two things come to mind:

1. 您可以仅在子进程中关闭 STDOUT/STDERR/STDIN(即 if (!fork()).这将允许父进程仍然使用它们，因为它们仍然在那里打开.

1. You can close STDOUT/STDERR/STDIN in just the child process (i.e. if (!fork()). This will allow the parent to still use them, because they'll still be open there.

我认为您可以使用更简单的 close(STDOUT) 而不是将其打开到/dev/null.

I think you can use the simpler close(STDOUT) instead of opening it to /dev/null.

例如:

if (!fork()) {
    close(STDIN) or die "Can't close STDIN: $!
";
    close(STDOUT) or die "Can't close STDOUT: $!
";
    close(STDERR) or die "Can't close STDERR: $!
";
    do_some_fork_stuff();
}

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