Galen has asked for the wisdom of the Perl Monks concerning the following question:

Hello, I hope someone can help me. This has got to be something simple. I'm having a problem pushing output from a DOS prompt into a file. Why does this work fine: 
system("dir>file");

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But this doesn't work: 
system("wget http://www.perlmonks.org>file");

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When I try the wget, output is to the terminal rather than a file.

Replies are listed 'Best First'.
Re: capture system output
by explorer (Chaplain) on Jan 18, 2006 at 20:41 UTC
    This work: 
    system("wget -o file http://www.perlmonks.org");

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    You can try the tap function at the Sysadm::Install module.
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[d/l]

      I think it's rather 

      system("wget -O file http://www.perlmonks.org");

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      (note the capital O).

      Update: on second thought, maybe it isn't. Depends on what you want to capture.

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[d/l]
      I have the file output within wget working, but it is harder to manipulate the output that way. I'll try tap, thanks.
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Re: capture system output
by Fletch (Bishop) on Jan 18, 2006 at 21:05 UTC

    Not that it's an answer to your difficulties with system, but rather than shelling out to wget consider LWP::Simple or LWP::UserAgent instead.

    Update: And if by "output" you mean the wget status information, that's getting written to STDERR not STDOUT so you'd need to redirect that instead.

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      I'm not as interested in the actual file retrieved. What I am looking to measure is the response time, so I want to see the output from wget showing when download began and completed. This is why I would prefer to parse the output within perl rather than capturing things I don't need into a file and parsing on the backend.
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        Again, just use LWP (and possibly Time::HiRes if you want finer than second granularity). 

        use LWP::Simple qw( get );
use Time::HiRes qw( time );

my $url = "http://...";

my $start = time;
getstore( $url, "/dev/null" );
my $end = time;

print "Took ", $end - $start, " seconds\n";

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[d/l]

        What's wrong with 

        use LWP::Simple qw( get );
use Time::HiRes qw( time );

my $url = "http://www.perlmonks.org/";

my $start_time = time;
get($url);
my $end_time = time;

print("The transfer took ", $end_time-$start_time, " seconds.\n");

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        You could easily put that into a loop and take the average (but beware of caching proxies).

        Update: oops, I was a bit slow at posting this!

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[d/l]

        My weblint program, available on CPAN, has a download timer: 

        $ weblint++ -t http://www.perlmonks.com
2.315 seconds

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        It's probably easier to do it yourself as some of the other posts showed you, though.

        --
        brian d foy <brian@stonehenge.com>
        Subscribe to The Perl Review
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