— create descriptor pair for
function creates a pipe, which is an object allowing
unidirectional data flow, and allocates a pair of file descriptors. The
first descriptor connects to the
of the pipe, and the second connects to the
end, so that data written to fildes appears
on (i.e., can be read from) fildes. 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 whose read or write end has been closed is
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 count.
function is identical to
pipe() except that the
non-blocking I/O mode on both ends of the pipe is determined by the
O_NONBLOCK flag in the flags
argument and the close-on-exec flag on both the new file descriptors is
determined by the
O_CLOEXEC flag in the
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
will succeed unless:
- Too many descriptors are active.
- The system file table is full.
- The fildes buffer is in an invalid area of the process's address space.
pipe2() may return the
- flags is invalid.
sh(1), fork(2), read(2), socketpair(2), write(2)
pipe() function conforms to
IEEE Std 1003.1-2008 (“POSIX.1”). The
pipe2() function is expected to conform to a future
revision of that standard.
As an extension, the pipe provided is actually capable of moving data bidirectionally. This is compatible with SVR4. However, this is non-POSIX behaviour which should not be relied on, for reasons of portability.
pipe() function call appeared in
Version 3 AT&T UNIX. Since
Version 4 AT&T UNIX, it allocates two
distinct file descriptors. The
appeared in OpenBSD 5.7.