PIPE
Section: System Calls (2)
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BSD mandoc
BSD 4
NAME
pipe
- create descriptor pair for interprocess communication
SYNOPSIS
Fd #include <unistd.h>
Ft int
Fn pipe int *fildes
DESCRIPTION
The
Fn 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
Fa fildes[1]
appears on (i.e., can be read from)
Fa 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
Fn pipe
call will fail if:
- Bq Er EMFILE
-
Too many descriptors are active.
- Bq Er ENFILE
-
The system file table is full.
- Bq Er EFAULT
-
The
Fa 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
Fn pipe
function call appeared in
AT&T System
v6 .
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUES
-
- ERRORS
-
- SEE ALSO
-
- HISTORY
-
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