pipe - create descriptor pair for interprocess communication
The pipe() function creates a pipe, which is an object allowing unidirectional
data flow, and allocates a pair of file descriptors.
descriptor connects to the read end of the pipe, and the
to the write 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
descriptors are closed.
A pipe whose read or write end has been closed is considered
Writing on such a pipe causes the writing process to receive
signal. Widowing a pipe is the only way to deliver end-offile to a
reader: after the reader consumes any buffered data, reading
pipe returns a zero count.
On successful creation of the pipe, zero is returned. Otherwise, a value
of -1 is returned and the variable errno set to indicate the
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
sh(1), fork(2), read(2), socketpair(2), write(2)
The pipe() function conforms to IEEE Std 1003.1-1988
As an extension, the pipe provided is actually capable of
bidirectionally. This is compatible with SVR4. However,
this is nonPOSIX
behaviour which should not be relied on, for reasons
A pipe() function call appeared in Version 3 AT&T UNIX.
OpenBSD 3.6 June 4, 1993
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