Here is my final Net::SSH::Perl example of locally breaking out of a running command on a remote host every 5 seconds, shutting down the old command, then starting up a new one (in a new SSH2 channel).

It's based upon using $ssh->channel_mgr->{channels} and $chan->rcvd_ieof neither of which are documented, but seem like the right interfaces to be using (comments?).

I'm thinking of following-up with the module author (Steffen Schwigon) to add and document the following methods to officially support this:

my @channels = $ssh->listChannels();
$ssh->closeChannel($channels[0]);

What do you think?

Thanks to all those who've helped me out on this issue!

-Craig

Title Update - This pretends we got an incoming EOF on the channel. WARNING: if you add a register_handler for stderr (and there is no activity on stderr), it seems to hang. I am investigating...

Update 2: - I like this solution because it is more efficient and elegant. However, there are too many side-effects, and I haven't the time to solve them all (need to get the author to advise). Here are some of the notes that helped me solve some of the side-effects that I discovered:

Re^4: Net::SSH::Perl hangs(during cmd), but only in Mason environment
Re^3: Net::SSH::Perl ConnectTimeout (ssh -o option)

use strict;
use warnings;

use Net::SSH::Perl;

my $HOST='MYHOST';
my $ID='MYLOGIN';
my $PW='MYPW';

my $DEBUG=0;    # 1 - provides ssh debug output

my $perlcmd = join('', <DATA>);
my $cmd = "/bin/perl -  -heartbeat ";

# Login to host...
my $myssh = Net::SSH::Perl->new( $HOST, protocol=>2, debug=>$DEBUG );
$myssh->login($ID, $PW) or die "Failed to login: $!\n";
listchannels($myssh);

# Alarm Handler...
$SIG{ALRM} = sub {
    print STDERR "\nALARM\n"; listchannels($myssh);

    # Close latest channel (pretend we received an EOF)...
    my $chanp = getchannels($myssh);
    $chanp->[-1]->rcvd_ieof;
};

# Startup a new command channel on HOST every 5 seconds...
while(1) {
    print STDERR "============================\n";
    alarm 5;
    remcount($myssh);          # Add new channel
    print STDERR "NEXT...\n";
}

sub listchannels
{
    my $ssh = shift || die "Missing ssh object";

    my $x=0;
    foreach my $c (@{getchannels($ssh)}) {
        if($c) { print STDERR "CHAN $x($c->{id}) :$c\n" }
        else { print STDERR "CHAN $x(X) --CLOSED--\n" };
        $x++;
    }
}

sub getchannels
{
    my $ssh = shift || die "Missing ssh object";

    return($myssh->channel_mgr->{channels});
}

sub remcount
{
    my $ssh = shift || die "Missing ssh object";

    # STDOUT handler (protocol 2 only)...
    $ssh->register_handler('stdout', sub {
        my ($channel, $buffer) = @_;
        print STDERR "CHAN $channel->{id}: ", $buffer->bytes, "\n";
    });

    print STDERR "REMOTE: $cmd\n";

    my ($stdout, $stderr, $exit) = $ssh->cmd($cmd, $perlcmd);
    print STDERR "DONE WITH COMMAND!!!\n";
}

__DATA__
use strict;
use warnings;

$|++;

my $c='a';
while(1) {
    print $c++;
    sleep 1;
}
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