PIPE(2)                              SysV                              PIPE(2)



NAME
     pipe - create an interprocess channel

SYNOPSIS
     int pipe (fildes)
     int fildes[2];

DESCRIPTION
     The pipe function creates a unidirectional interprocess channel called a
     pipe, and returns two file descriptors, fildes[0] and fildes[1]. The file
     descriptor specified by the fildes[0] argument is opened for reading and
     the file descriptor specified by the fildes[1] argument is opened for
     writing.  Their integer values will be the two lowest available at the
     time of the call to the pipe function.  The O_NONBLOCK flag will be clear
     on both file descriptors.  (The fcntl function can be used to set the
     O_NONBLOCK flag.)

     Up to 5120 bytes of data are buffered by the pipe before the writing
     process is blocked.  A read-only file descriptor fildes[0] accesses the
     data written to fildes[1] on a first-in-first-out (FIFO) basis.


     A process has the pipe open for reading if it has a file descriptor open
     that refers to the read end, fildes[0].  A process has the pipe open for
     writing if it has a file descriptor open that refers to the write end,
     fildes[1].  A read on file descriptor fildes[0] accesses the data written
     to fildes[1] on a first-in, first-out (FIFO) basis.

     Upon successful completion, the pipe function marks the st_atime,
     st_ctime and st_mtime fields of the pipe for update.

     The FD_CLOEXEC flag will be clear on both file descriptors.

DIAGNOSTICS
     Upon successful completion, a value of 0 is returned.  Otherwise, a value
     of -1 is returned and errno is set to indicate the error.

ERRORS
     pipe will fail if any of the following is true:

     [EMFILE]  NOFILES file descriptors are currently open.

     [ENFILE]  The system file table is full.

SEE ALSO
     read(2), write(2).
     sh(1) in the SysV Command Reference.