问如何在Perl中获得外部命令的输出？

EN

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]+/, $output) {
  ## Regular expression magic to grab what you want
}

use strict;
use warnings;

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

system 'powercfg', '-l';

system "powercfg -l";

my $str = `powercfg -l`;