blocks|key|1445271|text|system+'powercfg',+'-l';|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1445272|是推荐的方式。如果你不介意产生一个子壳，|unstyled|1445273|system+"powercfg+-l";|1445274|也行得通。如果您想要字符串形式的结果：|1445275|my+$str+=+`powercfg+-l`;|1445276|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|P|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|I|3|J|5|F|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$B|C]]|$1|M|3|-4|5|F|7|T|8|@]|9|@]|A|$]]]|N|$]]

<pre><code>system 'powercfg', '-l';
</code></pre>

is the recommended way. If you don't mind spawning a subshell,

<pre><code>system "powercfg -l";
</code></pre>

will work, too. And if you want the results in a string:

<pre><code>my $str = `powercfg -l`;
</code></pre>

blocks|key|1230399|text|尝试使用>运算符将输出转发到文件，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1230400|powercfg+-l+>+output.txt|code-block|syntax|javascript|1230401|然后打开output.txt并处理它。|1230402|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Try using > operator to forward the output to a file, like:

<pre><code>powercfg -l &gt; output.txt
</code></pre>

And then open output.txt and process it.

blocks|key|1230494|text|不需要先将命令的输出保存到文件中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1230495|my+$output+=+`powercfg+-l`;|code-block|syntax|javascript|1230496|请参见Quote-Like+Operators中的qx//。|offset|length|style|CODE|1230497|但是，如果您确实希望首先将输出保存到文件中，则可以使用：|1230498|my+$output_file+=+'output.txt';

system+"powercfg+-l+>+$output_file";

open+my+$fh,+'<',+$output_file+
++++or+die+"Cannot+open+'$output_file'+for+reading:+$!";

while+(+my+$line+=+<$fh>+)+{
++++#+process+lines
}

close+$fh;|1230499|参见perldoc+-f+system。|1230500|entityMap|0|LINK|mutability|MUTABLE|url|http://perldoc.perl.org/perlop.html#Quote-Like-Operators|1|http://perldoc.perl.org/functions/system.html^0|0|0|P|4|3|K|0|0|0|0|2|H|1|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|14|8|@$I|15|J|16|K|L]]|9|@$I|17|J|18|1|19]]|A|$]]|$1|M|3|N|5|6|7|1A|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|1C|8|@]|9|@$I|1D|J|1E|1|1F]]|A|$]]|$1|S|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]|10|$5|V|W|X|A|$Y|11]]]]

There is no need to first save the output of the command in a file:

<pre><code>my $output = `powercfg -l`;
</code></pre>

See <code>qx//</code> in <a href="http://perldoc.perl.org/perlop.html#Quote-Like-Operators" rel="noreferrer">Quote-Like Operators</a>.

However, if you do want to first save the output in a file, then you can use:

<pre><code>my $output_file = 'output.txt';

system "powercfg -l &gt; $output_file";

open my $fh, '&lt;', $output_file 
 or die "Cannot open '$output_file' for reading: $!";

while ( my $line = &lt;$fh&gt; ) {
 # process lines
}

close $fh;
</code></pre>

See <a href="http://perldoc.perl.org/functions/system.html" rel="noreferrer">perldoc -f system</a>.

blocks|key|1230522|text|my+$output+=+qx(powercfg+-l);

##+You've+got+your+output+loaded+into+the+$output+variable.+
##+Still+want+to+write+it+to+a+file?
open+my+$OUTPUT,+'>',+'output.txt'+or+die+"Couldn't+open+output.txt:+$!\n";
print+$OUTPUT+$output;
close+$OUTPUT

##+Now+you+can+loop+through+each+line+and
##+++parse+the+$line+variable+to+extract+the+info+you+are+looking+for.
foreach+my+$line+(split+/[\r\n]%2B/,+$output)+{
++##+Regular+expression+magic+to+grab+what+you+want
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1230523|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>my $output = qx(powercfg -l);

## You've got your output loaded into the $output variable. 
## Still want to write it to a file?
open my $OUTPUT, '&gt;', 'output.txt' or die "Couldn't open output.txt: $!\n";
print $OUTPUT $output;
close $OUTPUT

## Now you can loop through each line and
## parse the $line variable to extract the info you are looking for.
foreach my $line (split /[\r\n]+/, $output) {
 ## Regular expression magic to grab what you want
}
</code></pre>

blocks|key|1445467|text|为了对Sinan的出色答案进行扩展，并更明确地回答您的问题：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1445468|注意:反引号告诉Perl执行命令并检索其输出：|1445469|#!/usr/bin/perl+-w
use+strict;


my+@output+=+`powercfg+-l`;
chomp(@output);+#+removes+newlines

my+$linecounter+=+0;++++
my+$combined_line;

foreach+my+$line(@output){
++++print+$linecounter%2B%2B.")";
++++print+$line."\n";+#prints+line+by+line

++++$combined_line+.=+$line;+#+build+a+single+string+with+all+lines
++++#+The+line+above+is+the+same+as+writing:
++++#+$combined_line+=+$combined_line.$line;
}

print+"\n";
print+"This+is+all+on+one+line:\n";
print+">".$combined_line."<";|code-block|syntax|javascript|1445470|您的输出(在我的系统上)将是：|1445471|0)
1)Existing+Power+Schemes+(*+Active)
2)-----------------------------------
3)Power+Scheme+GUID:+381b4222-f694-41f0-9685-ff5bb260df2e++(Balanced)+*
4)Power+Scheme+GUID:+8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c++(High+performance)
5)Power+Scheme+GUID:+a1841308-3541-4fab-bc81-f71556f20b4a++(Power+saver)

This+is+all+on+one+line:
>Existing+Power+Schemes+(*+Active)-----------------------------------Power+Scheme+GUID:+381b4222-f694-41f0-9685-ff5bb260df2e++(Balanced)+*Power+Scheme+GUID:+8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c++(High+performance)Power+Scheme+GUID:+a1841308-3541-4fab-bc81-f71556f20b4a++(Power+saver)<|1445472|Perl让这一切变得很容易！|1445473|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

To expand on Sinan's excellent answer and to more explicitly answer your question:

NOTE: backticks `` tell Perl to execute a command and retrieve its output:

<pre><code>#!/usr/bin/perl -w
use strict;


my @output = `powercfg -l`;
chomp(@output); # removes newlines

my $linecounter = 0; 
my $combined_line;

foreach my $line(@output){
 print $linecounter++.")";
 print $line."\n"; #prints line by line

 $combined_line .= $line; # build a single string with all lines
 # The line above is the same as writing:
 # $combined_line = $combined_line.$line;
}

print "\n";
print "This is all on one line:\n";
print "&gt;".$combined_line."&lt;";
</code></pre>

Your output (on my system) would be:

<pre><code>0)
1)Existing Power Schemes (* Active)
2)-----------------------------------
3)Power Scheme GUID: 381b4222-f694-41f0-9685-ff5bb260df2e (Balanced) *
4)Power Scheme GUID: 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c (High performance)
5)Power Scheme GUID: a1841308-3541-4fab-bc81-f71556f20b4a (Power saver)

This is all on one line:
&gt;Existing Power Schemes (* Active)-----------------------------------Power Scheme GUID: 381b4222-f694-41f0-9685-ff5bb260df2e (Balanced) *Power Scheme GUID: 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c (High performance)Power Scheme GUID: a1841308-3541-4fab-bc81-f71556f20b4a (Power saver)&lt;
</code></pre>

Perl makes it easy!

blocks|key|1230602|text|你已经有了一些很好的答案。此外，如果只想处理命令的输出，而不需要将输出直接发送到文件，则可以在命令和Perl脚本之间建立管道。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1230603|use+strict;
use+warnings;

open(my+$fh,+'-%7C',+'powercfg+-l')+or+die+$!;
while+(my+$line+=+<$fh>)+{
++++#+Do+stuff+with+each+$line.
}|code-block|syntax|javascript|1230604|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You have some good answers already. In addition, if you just want to process a command's output and don't need to send that output directly to a file, you can establish a pipe between the command and your Perl script.

<pre><code>use strict;
use warnings;

open(my $fh, '-|', 'powercfg -l') or die $!;
while (my $line = &lt;$fh&gt;) {
 # Do stuff with each $line.
}
</code></pre>

I want to have output of Windows command-line program (say, <code>powercfg -l</code>) written into a file which is created using Perl and then read the file line by line in a for loop and assign it to a string.

How do I get the output of an external command in Perl?

我希望将Windows命令行程序(比如powercfg -l)的输出写入一个使用Perl创建的文件中，然后在for循环中逐行读取该文件，并将其分配给一个字符串。

问如何在Perl中获得外部命令的输出？
EN

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问如何在Perl中获得外部命令的输出？
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