PIPE(2)                              BSD                               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 5120 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 descriptors closed) returns an end-of-file.

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

ERRORS
     The pipe call will fail if one of the following occurs:

     [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'
                address space.

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

DIAGNOSTICS
     The function value 0 is returned if the pipe was created; -1 if an error
     occurred.

BUGS
     Should more than 5120 bytes be necessary in any pipe among a loop of
     processes, deadlock will occur.