Useless Use of "dd" (2015)
In the bad old Linux days, if you read a huge amount of data off the disk (like if you were doing a backup) Linux would try to take all that data and jam it in the page cache. This would push out all the useful stuff in your cache, and sometimes even cause swapping as Linux helpfully swaps out stuff to make room for more useless page cache.<p>One of the great things about `dd` is that you have a lot of control how the input and output files are opened. You can bypass the page cache when reading data by using iflag=direct, which would stop this from happening.