$exp->send("$command ; echo COMMAND_RET:$? | sed 's/^/COMMAND_OUT: /g'; echo -n END_; echo EXPECT\n"); 

##</code><code>##

my $cmd = "$command ; echo COMMAND_RET:$? | sed 's/^/COMMAND_OUT: /g'; echo -n END_; echo EXPECT\n";
warn "Sending command [$cmd]";
$exp->send($cmd);

##</code><code>##

my $cmd = sprintf q{%s; echo COMMAND_RET:$? | sed 's/^/COMMAND_OUT: /g'; echo -n END_; echo EXPECT\n}, $command;
warn "Sending command [$cmd]";
$exp->send($cmd);