*nix Documentation Project
·  Home
 +   man pages
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

  man pages->FreeBSD man pages -> pipe (2)              



NAME    [Toc]    [Back]

     pipe -- create descriptor pair for interprocess communication

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #include <unistd.h>

     pipe(int *fildes);

DESCRIPTION    [Toc]    [Back]

     The pipe() system call creates a pipe, which is an object allowing bidirectional
 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

     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 direction.

RETURN VALUES    [Toc]    [Back]

     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

ERRORS    [Toc]    [Back]

     The pipe() system 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 address space.

SEE ALSO    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

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

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

FreeBSD 5.2.1			 June 4, 1993			 FreeBSD 5.2.1
[ Back ]
 Similar pages
Name OS Title
socket Tru64 Create an end point for communication and return a descriptor
ftok Tru64 Generate a standard interprocess communication key
ipc Linux System V interprocess communication mechanisms
stdipc IRIX standard interprocess communication package
unix Linux Sockets for local interprocess communication.
ipcs HP-UX report status of interprocess communication facilities
ipcs Tru64 Reports Interprocess Communication (IPC) facility status
ipcs OpenBSD report System V interprocess communication facilities status
pipcs HP-UX report status of POSIX interprocess communication facilities
ipcs FreeBSD report System V interprocess communication facilities status
Copyright © 2004-2005 DeniX Solutions SRL
newsletter delivery service