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PIPE(2)			    BSD	System Calls Manual		       PIPE(2)

NAME
     pipe -- create descriptor pair for	interprocess communication

SYNOPSIS
     #include <unistd.h>

     int
     pipe(int *fildes);

DESCRIPTION
     The pipe()	function creates a pipe, which is an object allowing bidirec-
     tional data flow, and allocates a pair of file descriptors.

     By	convention, the	first descriptor is normally used as the read end of
     the pipe, and the second is normally the write end, so that data written
     to	fildes[1] appears on (i.e., can	be read	from) fildes[0].  This allows
     the output	of one program to be sent to another program: the source's
     standard output is	set up to be the write end of the pipe,	and the	sink's
     standard input is set up to be the	read end of the	pipe.  The pipe	itself
     persists until all	its associated descriptors are closed.

     A pipe that has had an end	closed is considered widowed.  Writing on such
     a pipe causes the writing process to receive a SIGPIPE signal.  Widowing
     a pipe is the only	way to deliver end-of-file to a	reader:	after the
     reader consumes any buffered data,	reading	a widowed pipe returns a zero
     count.

     The bidirectional nature of this implementation of	pipes is not portable
     to	older systems, so it is	recommended to use the convention for using
     the endpoints in the traditional manner when using	a pipe in one direc-
     tion.

RETURN VALUES
     On	successful creation of the pipe, zero is returned. Otherwise, a	value
     of	-1 is returned and the variable	errno set to indicate the error.

ERRORS
     The pipe()	call will fail if:

     [EMFILE]  Too many	descriptors are	active.

     [ENFILE]  The system file table is	full.

     [EFAULT]  The fildes buffer is in an invalid area of the process's	ad-
	       dress space.

SEE ALSO
     sh(1), fork(2), read(2), socketpair(2), write(2)

HISTORY
     A pipe() function call appeared in	Version	3 AT&T UNIX.

     Bidirectional pipes were first used on Unix System	V release 4.

4th Berkeley Distribution	 June 4, 1993	     4th Berkeley Distribution

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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