By using our site, you acknowledge that you have read and understand our Cookie Policy , Privacy Policy , and our Terms of Service. It only takes a minute to sign up. As far as I understand, named pipes are not written to disk but are stored in memory. Here's how I created a named pipe -.
Using Named Pipes (FIFOs) with Bash
After this, I restarted my system. However, even after the restart, I see pipe21 in my current directory. Why is that? No they're written to disk. The command mkfifo pipe21 creates the corresponding device on your filesystem. FIFOS don't necessarily have to be kept in this directory.
A named pipe is part of the filesystem.
Named pipe
Anything that has a filename is part of the filesystem. If that happens to be a filesystem in persistent storage i. A filesystem entry for a named pipe just has a name, the usual metadata time, permissions, etc. The data that goes through the pipe doesn't go to the filesystem. But the named pipe itself is in the filesystem. Sign up to join this community.
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The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. It can be opened by multiple processes for reading or writing. When processes are exchanging data via the FIFO, the kernel passes all data internally without writing it to the filesystem. Thus, the FIFO special file has no contents on the filesystem; the filesystem entry merely serves as a reference point so that processes can access the pipe using a name in the filesystem. The kernel maintains exactly one pipe object for each FIFO special file that is opened by at least one process.
The FIFO must be opened on both ends reading and writing before data can be passed. Normally, opening the FIFO blocks until the other end is opened also. So actually a named pipe does nothing until some process reads and writes to it. It does not take any space on the hard disk except a little bit of meta information , it does not use the CPU.
Don't forget to kill gzip, using kill You can redirect almost everything using named pipe. As example you can see this one line proxy. Also here is one more nice explanation of named pipe usage. It is much faster, and does not load network resources.
For example your Web Server can communicate with the database directly using a named pipe, instead of using localhost address or listening to some port. It is true that you won't use system memory but the fact you don't use cpu in your example is only because you don't read the pipe so the process is waiting.
Why use a named pipe instead of a file? - Ask Ubuntu
So basically the named pipe saves you here a read and write of 1G plus some filesystem cleaning since we wrote nothing to the filesystem but the empty fifo node. It is even more interesting when you work with SSDs since they have a limited number of writes before cells die.
Nevertheless you would be limited by the size of the RAM disk, whereas the "named pipe trick" has no limits. You can let a program lie still and listen to a named pipe for some outside event. As soon as the outside event occurs f.
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When the close statement is issued, the listening program will receive the stream of data through the pipe via a read statement, and is ready to process what it has got. Don't forget tor close the pipe after reading the content. The listening program could also return results of its processing via the same, or via another named pipe. Such inter-program communications is very convenient at times.
Ubuntu Community Ask! Home Questions Tags Users Unanswered. Why use a named pipe instead of a file?
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