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NAME
     pipe - create an interprocess channel

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

     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
     returned in r1 (resp. fildes[1]), up to 4096 bytes of data
     are buffered before the writing process is suspended.  A
     read using the descriptor returned in r0 (resp. fildes[0])
     will pick up the 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) return an end-of-
     file.  Write calls under similar conditions generate a fatal
     signal (signal (II)); if the signal is ignored, an error is
     returned on the write.

SEE ALSO
     sh (I), read (II), write (II), fork (II)

DIAGNOSTICS
     The error bit (c-bit) is set if too many files are already
     open.  From C, a -1 returned value indicates an error.  A
     signal is generated if a write on a pipe with only one end
     is attempted.

BUGS

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