2

Using Perl 5.8.8 on Linux, need the output of a perl 'system' command to be hidden. The command in my code is: 

system("wget", "$url", "-Omy_folder/$date-$target.html", "--user-agent=$useragent");

I've tried using > /dev/null 2>&1 in different places in the system command, like this: 

system("wget", "$url", "-Omy_folder/$date-$target.html", "--user-agent=$useragent","> /dev/null 2>&1");

Can anyone help me with where the redirection to /dev/null should be?

splattne
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1 Answers1

3

When you call system() with more than one arg, you are telling perl to pass it directly to one of the exec*() calls, so it will not be called with a shell. The shell is the thing that understands file redirection. Try this:

system("wget $url -Omy_folder/$date-$target.html --user-agent=$useragent >/dev/null 2>&1");

Note that this is technically less secure than passing it straight to exec.

For quoting use String::ShellQuote, or just implement the logic yourself:

sub sq {
  my $str = shift;

  if (!$str) {
    $str = "''";
  } else {
    $str =~ s|'|'\\''|g;
    $str = "'$str'";
    $str =~ s|^''||;
    $str =~ s|''$||;
  }

  return($str);
}

$useragent = sq($useragent);
system("wget $url -Omy_folder/$date-$target.html --user-agent=$useragent >/dev/null 2>&1");

Also, to make this a little more sys-admin-y and a little less programmer-y, have you considered using the -q option to wget instead of jumping through the shell/file redirection hoops?

jj33
  • 11,268
  • that would work, except the $useragent string contains '(' characters, I need to escape those somehow ... –  Apr 01 '10 at 20:17