4.3BSD - /usr/man/cat2/pipe.0

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) coop‐
       erating 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) 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)