This article is about anonymous pipes, where data written by one process is buffered by the operating system until it is read by the next process, and this uni-directional channel disappears when the processes are completed. This differs from named pipes, where messages are passed to or from a pipe that is named by making it a file, and remains after the processes are completed. The standard shell syntax for anonymous pipes is to list multiple commands, separated by vertical bars ("pipes" in common Unix verbiage):