pipe(2) [plan9 man page]

PIPE(2) 							System Calls Manual							   PIPE(2)

NAME

       pipe - create an interprocess channel

SYNOPSIS

       #include <u.h>
       #include <libc.h>

       int pipe(int fd[2])

DESCRIPTION

       Pipe  creates  a  buffered  channel for interprocess I/O communication.	Two file descriptors are returned in fd.  Data written to fd[1] is
       available for reading from fd[0] and data written to fd[0] is available for reading from fd[1].

       After the pipe has been established, cooperating processes created by subsequent fork(2) calls may pass data through the pipe with read and
       write  calls.   The bytes placed on a pipe by one write are contiguous even if many processes are writing.  Write boundaries are preserved:
       each read terminates when the read buffer is full or after reading the last byte of a write, whichever comes first.

       The number of bytes available to a read(2) is reported in the Length field returned by fstat or dirfstat on a pipe (see stat(2)).

When all the data has been read from a pipe and the writer has closed the pipe or exited,
       read(2) will return 0 bytes.  Writes to a pipe with no reader will generate a note sys: write on closed pipe.

SOURCE

       /sys/src/libc/9syscall

SEE ALSO

       intro(2), read(2), pipe(3)

DIAGNOSTICS

       Sets errstr.

BUGS

       If a read or a write of a pipe is interrupted, some unknown number of bytes may have been transferred.
       When a read from a pipe returns 0 bytes, it usually means end of file but is indistinguishable from reading the result of an explicit write
       of zero bytes.

																	   PIPE(2)

PIPE(2) 						      BSD System Calls Manual							   PIPE(2)

NAME

     pipe -- create descriptor pair for interprocess communication

SYNOPSIS

     #include <unistd.h>

     int
     pipe(int *fildes);

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.

RETURN VALUES

     On successful creation of the pipe, zero is returned. Otherwise, a value of -1 is returned and the variable errno set to indicate the error.

ERRORS

     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 process's address space.

SEE ALSO

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

HISTORY

     A pipe() function call appeared in Version 6 AT&T UNIX.

4th Berkeley Distribution					   June 4, 1993 					 4th Berkeley Distribution