Named pipes are created with the mkfifo command. This command will create a named pipe called "geek-pipe" in the current directory. Let's extend things again. We'll take the wc command off the command line and replace it with awk. There are nine columns in the output from ls with the -l (long format) option. We'll use awk to print columns five, three, and nine. These are the size, owner, and name of the file. Nothing much will appear to happen. You may notice that you don't get returned to the command prompt though, so something is going on.

We'll now pass that output through the sort command. We'll use the -n (numeric) option to let sort know the first column should be treated as numbers. in the other, so you can differentiate between them. The hash "#" tells the shell that what follows is a comment, and to ignore it. Named pipes appear as persistent objects in the filesystem, so you can see them using ls. They're persistent because they will survive a reboot of the computer---although any unread data in them at that time will be discarded.

Named pipes were used a lot at one time to allow different processes to send and receive data, but I haven't seen them used that way for a long time. No doubt there are people out there still using them to great effect, but I've not encountered any recently. But for completeness' sake, or just to satisfy your curiosity, here's how you can use them. The reamer or scoop is a flat instrument shaped like a dull knife blade or a flattened spoon, used to scrape ash and unburned tobacco ( dottle) off the sides and bottom of a pipe.

We'll finish off by adding in the tail command. We'll tell it to list the last five lines of output only. Let's use our pipe. The unnamed pipes we used in our previous examples passed the data immediately from the sending command to the receiving command. Data sent through a named pipe will stay in the pipe until it is read. The data is actually held in memory, so the size of the named pipe will not vary in ls listings whether there is data in it or not.cut: Cuts the string at the first occurrence of the specified delimiter ".". Text after this is discarded. Suppose we have a directory full of many different types of file. We want to know how many files of a certain type are in that directory. There are other ways to do this, but the object of this exercise is to introduce pipes, so we're going to do it with pipes. Let's take the entirety of our previous example and redirect that into the named pipe. So we're using both unnamed and named pipes in one command: