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PIPE(2)			  FreeBSD System Calls Manual		       PIPE(2)

NAME
     pipe -- create descriptor pair for	interprocess communication

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     pipe(int *fildes);

DESCRIPTION
     The pipe()	system call creates a pipe, which is an	object allowing	bidi-
     rectional 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
     The pipe()	function returns the value 0 if	successful; otherwise the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     The pipe()	system call will fail if:

     [EMFILE]		Too many descriptors are active.

     [ENFILE]		The system file	table is full.

     [ENOMEM]		Not enough kernel memory to establish a	pipe.

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

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

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

     Bidirectional pipes were first used on AT&T System	V Release 4 UNIX.

FreeBSD	9.2		       January 30, 2006			   FreeBSD 9.2

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

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