[英]Redirecting STDOUT of a pipe in Perl
I feel as though there should be a simple way to do this, but searching around gives me no good leads. 我觉得似乎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。 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. 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
。
open(my $foo, '|-', '/path/to/foo');
print $foo 'input'; # Should behave equivalently to "print 'output'"
close($foo);
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? 有没有简单的方法可以做到这一点,或者我遇到了Perl众多“无法从这里到达那里”的时刻之一?
The subprocess will inherit STDOUT automatically. 子进程将自动继承STDOUT。 This works for me:
这对我有用:
open(my $f, "|-", "cat");
print $f "hi\n";
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. 如果不是真的立即关闭管道,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"
。 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: 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:
open(my $f, "|-", "cat");
print $f "hi\n";
sleep(10);
close($f); # or exit
# now output appears
Try adding select $f; $| = 1
尝试添加
select $f; $| = 1
select $f; $| = 1
select $f; $| = 1
(or I think the more modern way is $f->autoflush(1)
) select $f; $| = 1
(或者我认为更现代的方法是$f->autoflush(1)
)
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