sub exec_command {
    my ($cmd_login, $ssh_bin, $startTime, $duration, $auth) = @_;
    system("doConnect() $cmd_login $ssh_bin $startTime $duration $auth");
}
while (...) {
    my $cmd_login = "$user\@$host";
    my ssh_bin = `which ssh`;
    chomp $ssh_bin;
    ...
    exec_command($cmd_login, $ssh_bin, $startTime, $duration, $auth);
}