在Perl中重定向管道的STDOUT [英] Redirecting STDOUT of a pipe in Perl

问题描述

我觉得应该有一个简单的方法来做到这一点，但是四处搜寻并没有给我带来好的线索.我只想open()到应用程序的管道，向其中写入一些数据，然后将子进程的输出发送到调用脚本的STDOUT.

I feel as though there should be a simple way to do this, but searching around gives me no good leads. I just want to open() a pipe to an application, write some data to it, and have the output of the subprocess sent to the STDOUT of the calling script.

open(my $foo, '|-', '/path/to/foo');
print $foo 'input'; # Should behave equivalently to "print 'output'"
close($foo);

是否有一种简单的方法可以做到这一点，或者在Perl中遇到了许多无法从这里到达那里"的事件之一?

Is there a simple way to do this, or have I hit upon one of the many "can't get there from here" moments in Perl?

推荐答案

子进程将自动继承STDOUT.这对我有用:

The subprocess will inherit STDOUT automatically. This works for me:

open(my $f, "|-", "cat");
print $f "hi\n";

如果您没有真正立即关闭管道，则问题可能出在另一端:默认情况下，STDOUT是行缓冲的，因此您会立即看到print "hello world\n".默认情况下，子进程的管道将使用块缓冲，因此您实际上可能正在等待perl脚本中的数据到达其他程序:

If you are not really closing the pipe immediately the problem might be on the other end: STDOUT is line-buffered by default, so you see print "hello world\n" immediately. The pipe to your subprocess will be block-buffered by default, so you may actually be waiting for the data from your perl script to reach the other program:

open(my $f, "|-", "cat");
print $f "hi\n";
sleep(10);
close($f); # or exit
# now output appears

尝试添加select $f; $| = 1(或者我认为更现代的方式是$f->autoflush(1))

Try adding select $f; $| = 1 (or I think the more modern way is $f->autoflush(1))

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