Misc. Reference	Manual Pages				 PIPE(II)


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


                   Last change: 8/5/73