To create a 10 MB file in Linux you can use following command. dd if=/dev/zero of=test.img bs=1024 count=0 seek=$[1024*10]

To change permission of folders and files under the public_html of a domain at once we can use the following script. find ./ -type d -exec chmod 755 {} \; find ./ -type f -exec chmod 644 {} \;