使用php和linux将文件从一个文件夹复制到已安装分区上的另一个文件夹

I installed apache2 server on my host. I want to copy the folder or files from on mounted drive to another mounted drive. I am using

system('sudo cp -rf /source/* /destination/')

in PHP to do this task. The problem is it doesn't executing from PHP but same command to the copying task from command line. There might be permission issue, but I am unable to figure out the reason. Have anybody done this, if yes please guide me.