public function executeCommand()
    {
        if ($this->rsyncPath === null) {
            throw new BuildException('The "rsyncPath" attribute is missing or undefined.');
        }

        if ($this->sourceDir === null) {
            throw new BuildException('The "sourcedir" attribute is missing or undefined.');
        } else {
            if ($this->destinationDir === null) {
                throw new BuildException('The "destinationdir" attribute is missing or undefined.');
            }
        }

        if (strpos($this->destinationDir, ':')) {
            $this->setIsRemoteConnection(true);
        }

        if (strpos($this->sourceDir, ':')) {
            if ($this->isRemoteConnection) {
                throw new BuildException('The source and destination cannot both be remote.');
            }
            $this->setIsRemoteConnection(true);
        } else {
            if (!(is_dir($this->sourceDir) && is_readable($this->sourceDir))) {
                throw new BuildException('No such file or directory: ' . $this->sourceDir);
            }
        }

        if ($this->backupDir !== null && $this->backupDir == $this->destinationDir) {
            throw new BuildException("Invalid backup directory: " . $this->backupDir);
        }

        $command = $this->getCommand();

        $output = [];
        $return = null;
        exec($command, $output, $return);

        $lines = '';
        foreach ($output as $line) {
            if (!empty($line)) {
                $lines .= "\r\n" . "\t\t\t" . $line;
            }
        }

        $this->log($command);

        if ($return != 0) {
            $this->log('Task exited with code: ' . $return, Project::MSG_ERR);
            $this->log(
                'Task exited with message: (' . $return . ') ' . $this->getErrorMessage($return),
                Project::MSG_ERR
            );
            throw new BuildException($return . ': ' . $this->getErrorMessage($return));
        } else {
            $this->log($lines, Project::MSG_INFO);
        }

        return $return;
    }