如何将 STDOUT 和 STDERR 重定向到变量 [英] How to redirect STDOUT and STDERR to a variable

问题描述

我想将 STDERR 和 STDOUT 重定向到一个变量.我做到了.

I want to redirect STDERR and STDOUT to a variable. I did this.

close(STDOUT);
close(STDERR);

my $out;
open(STDOUT, ">>", \$out);
open(STDERR, ">>", \$out);

for(1..10)
{
    print "print\n"; # this is ok. 
    warn "warn\n"; # same
    system("make"); # this is lost. neither in screen nor in variable.
}

system 的问题.我也希望捕获此调用的输出.

The problem with system. I want the output of this call to be captured too.

推荐答案

您是否想在变量中捕获输出?如果是这样，您可以使用带有适当重定向的反引号或 qx{}.例如，您可以使用:

Are you seeking to capture the output in a variable? If so, you have use backticks or qx{} with appropriate redirection. For example, you could use:

#/usr/bin/env perl
use strict;
use warnings;

# Ensure we have a way to write messages
open my $fh, '>', "output" or die;

close(STDOUT);
close(STDERR);

my $out;
open(STDOUT, ">>", \$out) or do { print $fh, "failed to open STDOUT ($!)\n"; die };
open(STDERR, ">>", \$out) or do { print $fh, "failed to open STDERR ($!)\n"; die };

foreach my $i (1..10)
{
    print "print $i\n"; 
    warn "warn $i\n";
    my $extra = qx{make pth$i 2>&1};
    print $fh "<<$i>><<$out>><<$extra>>\n";
}

(我碰巧在目录中有 pth1、pth2 和 pth3 程序 - 它们被设置为正常；pth4 及以上将错误写入 stderr；重定向是必要的.)

(I happen to have programs pth1, pth2 and pth3 in the directory - they were made OK; pth4 and above write errors to stderr; the redirection was necessary.)

你应该经常检查open()等操作是否成功.

You should always check the success of operations such as open().

为什么需要这样做?因为写入变量需要进行写入的进程的合作 - 而 make 不知道如何合作.

Why is this necessary? Because writing to a variable requires the cooperation of the process doing the writing - and make doesn't know how to cooperate.

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