Read pipe data

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pipe

PIPE(2) 							System Calls Manual							   PIPE(2)

NAME

       pipe - create an interprocess channel

SYNOPSIS

       pipe(fildes)
       int fildes[2];

DESCRIPTION

       The pipe system call creates an I/O mechanism called a pipe.  The file descriptors returned can be used in read and write operations.  When
       the pipe is written using the descriptor fildes[1] up to 4096 bytes of data are buffered before the writing process is suspended.   A  read
       using  the  descriptor  fildes[0] will pick up the data.  Writes with a count of 4096 bytes or less are atomic; no other process can inter-
       sperse data.

       It is assumed that after the pipe has been set up, two (or more) cooperating processes (created by subsequent fork calls)  will	pass  data
       through the pipe with read and write calls.

       The Shell has a syntax to set up a linear array of processes connected by pipes.

       Read calls on an empty pipe (no buffered data) with only one end (all write file descriptors closed) returns an end-of-file.

SEE ALSO

       sh(1), read(2), write(2), fork(2)

DIAGNOSTICS

       The  function value zero is returned if the pipe was created; -1 if too many files are already open.  A signal is generated if a write on a
       pipe with only one end is attempted.

BUGS

       Should more than 4096 bytes be necessary in any pipe among a loop of processes, deadlock will occur.

ASSEMBLER

       (pipe = 42.)
       sys pipe
       (read file descriptor in r0)
       (write file descriptor in r1)

																	   PIPE(2)

Shell Programming and Scripting