ag4ve has asked for the wisdom of the Perl Monks concerning the following question:

I'm running up against the pipe buffer doing this:

      my $success = run 
          [$echo => -e => "\'" => join("\n", @iptout) => "\'"], 
          '|', [$ipt_cmd => 'iptables-restore'], 
          '>', \my $cmdout, '2>&1';

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Error:

exec failed: Argument list too long at ./firewall.pl line 852

So, I figured I'd try this:

      my $success = run 
          [$ipt_cmd => 'iptables-restore'], 
          '>', \my $cmdout, '2>&1',
          '<<<', '${', [$echo => -e => "\'" => join("\n", @iptout) => 
+"\'"], '}';

[download]

Error:

No such file or directory: open( <<, 0x000 ) at ./firewall.pl line 852

But I can't figure out how to get it in proper syntax for IPC::Run? Also, per the limit I'm hitting 'man 7 pipe (I'm running 3.10+ on 64 bit, but this is the latest pipe manpage): In Linux versions before 2.6.11, the capacity of a pipe was the same as the system page size (e.g., 4096 bytes on i386). Since Linux 2.6.11, the pipe capacity is 65536 bytes.

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Re: IPC::Run / bash pipe
by runrig (Abbot) on Nov 07, 2013 at 00:56 UTC

    What is '<<<' supposed to be?

    Also, I'm not sure what you're trying to accomplish with the quoting, but I don't think you're doing it correctly. If you have the input for your command in a string, then just use it:
    use IPC::Run qw(run);

my @arr = qw(
abc
def
);

my $input = join("", map "$_\n", @arr);
run [ sed => 's/[ad]/o/' ], "<", \$input, ">", \my $output;
print "O: [$output]\n";

    [download]

    Or compare these various quoting strategies (the first is similar to yours and I believe incorrect, the last is more like what I think you're trying to accomplish):

    use IPC::Run qw(run);

my @arr = qw(
abc
def
);
run [ echo => q(') => join("\n", @arr) => q(') ], ">", \my $output;
print "O: [$output]\n";

run [ echo => q(') . join("\n", @arr) . q(') ], ">", \my $output;
print "O: [$output]\n";

run [ echo => join("\n", @arr) ], ">", \my $output;
print "O: [$output]\n";

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[select]

      This is the syntax I'm going for:

      grep ba > t.txt 2>&1 <<< $(echo -e "foo\nbar\nbaz")

      To demonstrate what I'm Looking at:

      #!/usr/bin/env perl

use strict;
use warnings;

use IPC::Run qw(run);

my $str;

my $count = 0;
while (1)
{
  $count += 10;
  $str .= "1111111111";

  run [echo => $str], '|', [grep => 'foo'];
  print "$count " unless ($count % 10000)
}

      [download]

      And if you don't feel like waiting for it, here's the result:

       % ./t2.pl
10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 110000 12
+0000 130000 exec failed: Argument list too long at ./t2.pl line 16.
 at ./t2.pl line 16.

      [download]

      If I don't use ipset (which are pretty long by their own, I'm under the limit. However, without ipset:

      # wc -c fw2.save
165670 fw2.save

      [download]

      I don't want to write a tempfile unless there's no other option, ulimit -s unlimited doesn't seem to make a difference, and I'm not sure about FFI::Raw and iptc.o / iptables.o (I'm looking into it).

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        Oh, nm, I'm blind (or not paying attention) - that works

              my $success = run 
          [$ipt_cmd => 'iptables-restore'], 
          '<', \(join("\n". @iptout)),
          '>', \my $cmdout, '2>&1';

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[reply]
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