perl - perlipc 文档中的错误？

Question

我试图解开我在 perlipc 中看到的东西文档。

If you're writing to a pipe, you should also trap SIGPIPE. Otherwise, think of what happens when you start up a pipe to a command that doesn't exist: the open() will in all likelihood succeed (it only reflects the fork()'s success), but then your output will fail--spectacularly. Perl can't know whether the command worked because your command is actually running in a separate process whose exec() might have failed. Therefore, while readers of bogus commands return just a quick end of file, writers to bogus command will trigger a signal they'd better be prepared to handle. Consider:

   open(FH, "|bogus")  or die "can't fork: $!";
   print FH "bang\n"   or die "can't write: $!";
   close FH            or die "can't close: $!";

That won't blow up until the close, and it will blow up with a SIGPIPE. To catch it, you could use this:

   $SIG{PIPE} = 'IGNORE';
   open(FH, "|bogus")  or die "can't fork: $!";
   print FH "bang\n"   or die "can't write: $!";
   close FH            or die "can't close: status=$?";

如果我没看错，它说第一个版本可能会在最后关闭之前消失。

但是，这不会发生在我的 OS X 机器上(Perl 版本 5.8.9 到 5.15.9)。它在 open 上爆炸不管我是否有 $SIG{PIPE} 行，都带有“无法 fork :没有这样的文件或目录”。

我有什么误解？

Answer 1

这是在 5.6 的开发过程中实现的更改，以便 system() 可以检测何时无法 fork/exec 子项

https://github.com/mirrors/perl/commit/d5a9bfb0fc8643b1208bad4f15e3c88ef46b4160

它也记录在 http://search.cpan.org/dist/perl/pod/perlopentut.pod#Pipe_Opens 中

它本身指向 perlipc，但 perlipc 似乎确实缺少这个