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BSD 2.11 - man page for pipe (bsd section 2)

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PIPE(2) 										  PIPE(2)

NAME
       pipe - create an interprocess communication channel

SYNOPSIS
       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  fildes[1]  up to 4096 bytes of data are buffered before the writing process is
       suspended.  A read using the descriptor 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  descrip-
       tors closed) returns an end-of-file.

       Pipes are really a special case of the socketpair(2) call and, in fact, are implemented as
       such in the system.

       A signal is generated if a write on a pipe with only one end is attempted.

RETURN VALUE
       The function value zero is returned if the pipe was created; -1 if an error occurred.

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 address space.

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

BUGS
       Should more than 4096 bytes be necessary in any pipe among a loop of  processes,  deadlock
       will occur.

4th Berkeley Distribution		 August 26, 1985				  PIPE(2)
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