DESCRIPTION
The
pipe() 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
read end of the pipe, and the second connects to the
write end, so that data written to
fildes[1] appears on (i.e., can be read from)
fildes[0]. 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 considered widowed. Writing 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.
The pipe2() function behaves exactly like pipe() only it allows extra flags to be set on the returned file descriptor. The following flags are valid:
-
O_CLOEXEC
-
Set the “close-on-exec” property.
-
O_NONBLOCK
-
Sets non-blocking I/O.