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Diffstat (limited to 'lib/libc/sys/pipe.2')
-rw-r--r-- | lib/libc/sys/pipe.2 | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/lib/libc/sys/pipe.2 b/lib/libc/sys/pipe.2 new file mode 100644 index 0000000..faf1a91 --- /dev/null +++ b/lib/libc/sys/pipe.2 @@ -0,0 +1,118 @@ +.\" Copyright (c) 1980, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)pipe.2 8.1 (Berkeley) 6/4/93 +.\" $FreeBSD$ +.\" +.Dd January 30, 2006 +.Dt PIPE 2 +.Os +.Sh NAME +.Nm pipe +.Nd create descriptor pair for interprocess communication +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In unistd.h +.Ft int +.Fn pipe "int *fildes" +.Sh DESCRIPTION +The +.Fn pipe +system call +creates a +.Em pipe , +which is an object allowing +bidirectional data flow, +and allocates a pair of file descriptors. +.Pp +By convention, the first descriptor is normally used as the +.Em read end +of the pipe, +and the second is normally the +.Em 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. +.Pp +A pipe that has had an end closed is considered +.Em widowed . +Writing on such a pipe causes the writing process to receive +a +.Dv 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. +.Pp +The bidirectional nature of this implementation of pipes is not +portable to older systems, so it is recommended to use the convention +for using the endpoints in the traditional manner when using a +pipe in one direction. +.Sh RETURN VALUES +.Rv -std pipe +.Sh ERRORS +The +.Fn pipe +system call will fail if: +.Bl -tag -width Er +.It Bq Er EMFILE +Too many descriptors are active. +.It Bq Er ENFILE +The system file table is full. +.It Bq Er ENOMEM +Not enough kernel memory to establish a pipe. +.It Bq Er EFAULT +The +.Fa fildes +buffer is in an invalid area of the process's address +space. +.El +.Sh SEE ALSO +.Xr sh 1 , +.Xr fork 2 , +.Xr read 2 , +.Xr socketpair 2 , +.Xr write 2 +.Sh HISTORY +The +.Fn pipe +function appeared in +.At v3 . +.Pp +Bidirectional pipes were first used on +.At V.4 . |