no ability to seek. To avoid deadlock and exploit parallelism, the Unix process with one or more new pipes will then, generally, call fork() to create new processes. Each process will then close the end(s) of the pipe that it will not be using before producing or consuming any data. Alternatively, a process might create new threads and use the pipe to communicate between them. Named pipes may also be created using mkfifo() or mknod() and then presented as the input or output file to programs as they are invoked. They allow multi-path pipes to be created, and are especially effective when combined with standard error redirection, or with tee. Implementation In most Unix-like systems, all processes of a pipeline are started at the same time, with their streams appropriately connected, and managed by the scheduler together with all other processes running on the machine. An important aspect of this, setting Unix pipes apart from other pipe implementations, is the concept of buffering: for example a sending program may produce 5000 bytes per second, and a receiving program may only be able to accept 100 bytes per second, but no data is lost. Instead, the output of the sending program is held in the buffer. When the receiving program is ready to read data, the next program in the pipeline reads from the buffer. If the buffer is filled, the sending program is stopped (blocked) until at least some data is removed from the buffer by the receiver. In Linux, the size of the buffer is 65,536 bytes (64KiB). An open source third-party filter called bfr is available to provide larger buffers if required. Network pipes Tools like netcat and socat can connect pipes to TCP/IP sockets. History The pipeline concept was invented by Douglas McIlroy and first described in the man pages of Version 3 Unix. McIlroy noticed that much of the time command shells passed the output file from one program as input to another. His ideas were implemented in 1973 when ("in one feverish night", wrote McIlroy) Ken Thompson added the pipe() system call and pipes to the shell and several utilities in Version 3 Unix. "The next day", McIlroy continued, "saw an unforgettable orgy of one-liners as everybody joined in the excitement of plumbing." McIlroy also credits Thompson with the | notation, which greatly simplified the description of pipe syntax in Version 4. Although developed independently,