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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.
Run a command with a time limit true: Does nothing, but exits successfully tty: Prints terminal name uname: Prints system information unlink: Removes the specified file using the unlink function uptime: Tells how long the system has been running users: Prints the user names of users currently logged into the current host who
splice() works by using the pipe buffer. A pipe buffer is an in-kernel memory buffer that is opaque to the userspace process. A user process can splice the contents of a source file into this pipe buffer, then splice the pipe buffer into the destination file, all without moving any data through userspace.
E.g., if the source process consists of a command which reads an audio track from a CD and the destination process consists of a command which compresses the waveform audio data to a format like MP3. In this case, buffering the entire track in a pipe buffer would allow the CD drive to spin down more quickly, and enable the user to remove the CD ...
PIPE selects programs to run and chains them together in a pipeline to pump data through. Because CMS programs and utilities don't provide a device independent stdin and stdout interface, CMS Pipelines has a built-in library of programs that can be called in a pipeline specification.
Every pipe is placed in the root directory of the named pipe filesystem (NPFS), mounted under the special path \\.\pipe\ (that is, a pipe named "foo" would have a full path name of \\.\pipe\foo). Anonymous pipes used in pipelining are actually named pipes with a random name. They are very rarely seen by users, but there are notable exceptions.
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This pipe will be accessible with something like /dev/fd/63; you can see it with a command like echo <(true). Execute the substituted command in the background (sort file2 in this case), piping its output to the anonymous pipe. Execute the primary command, replacing the substituted command with the path of the anonymous pipe.