111 lines
4.5 KiB
HTML
111 lines
4.5 KiB
HTML
<head>
|
|
<title>pipe(3) - Plan 9 from User Space</title>
|
|
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
|
|
</head>
|
|
<body bgcolor=#ffffff>
|
|
<table border=0 cellpadding=0 cellspacing=0 width=100%>
|
|
<tr height=10><td>
|
|
<tr><td width=20><td>
|
|
<tr><td width=20><td><b>PIPE(3)</b><td align=right><b>PIPE(3)</b>
|
|
<tr><td width=20><td colspan=2>
|
|
<br>
|
|
<p><font size=+1><b>NAME </b></font><br>
|
|
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
|
|
|
pipe – create an interprocess channel<br>
|
|
|
|
</table>
|
|
<p><font size=+1><b>SYNOPSIS </b></font><br>
|
|
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
|
|
|
<tt><font size=+1>#include <u.h><br>
|
|
#include <libc.h>
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
|
</font></tt>
|
|
<tt><font size=+1>int pipe(int fd[2])<br>
|
|
</font></tt>
|
|
</table>
|
|
<p><font size=+1><b>DESCRIPTION </b></font><br>
|
|
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
|
|
|
<i>Pipe</i> creates a buffered channel for interprocess I/O communication.
|
|
Two file descriptors are returned in <i>fd</i>. Data written to <tt><font size=+1>fd[1]</font></tt>
|
|
is available for reading from <tt><font size=+1>fd[0]</font></tt> and data written to <tt><font size=+1>fd[0]</font></tt>
|
|
is available for reading from <tt><font size=+1>fd[1]</font></tt>.
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
|
|
|
After the pipe has been established, cooperating processes created
|
|
by subsequent <a href="../man2/fork.html"><i>fork</i>(2)</a> calls may pass data through the pipe with
|
|
<i>read</i> and <i>write</i> calls.
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
|
|
|
When all the data has been read from a pipe and the writer has
|
|
closed the pipe or exited, <a href="../man3/read.html"><i>read</i>(3)</a> will return 0 bytes. Writes
|
|
to a pipe with no reader will generate a note <tt><font size=+1>sys: write on closed
|
|
pipe</font></tt>.<br>
|
|
|
|
</table>
|
|
<p><font size=+1><b>SOURCE </b></font><br>
|
|
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
|
|
|
<tt><font size=+1>/usr/local/plan9/src/lib9/pipe.c<br>
|
|
</font></tt>
|
|
</table>
|
|
<p><font size=+1><b>SEE ALSO </b></font><br>
|
|
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
|
|
|
<a href="../man3/intro.html"><i>intro</i>(3)</a>, <a href="../man3/read.html"><i>read</i>(3)</a><br>
|
|
|
|
</table>
|
|
<p><font size=+1><b>DIAGNOSTICS </b></font><br>
|
|
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
|
|
|
Sets <i>errstr</i>.<br>
|
|
|
|
</table>
|
|
<p><font size=+1><b>BUGS </b></font><br>
|
|
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
|
|
|
|
If a read or a write of a pipe is interrupted, some unknown number
|
|
of bytes may have been transferred.
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
|
|
|
<i>Pipe</i> is a macro defined as <i>p9pipe</i> to avoid name conflicts with
|
|
Unix’s <i>pipe</i> system call.
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
|
|
|
Unix pipes are not guaranteed to be bidirectional. In order to
|
|
ensure a bidirectional channel, <i>p9pipe</i> creates Unix domain sockets
|
|
via the <a href="../man2/socketpair.html"><i>socketpair</i>(2)</a> instead of Unix pipes.
|
|
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
|
|
|
|
The implementation of pipes as Unix domain sockets causes problems
|
|
with some Unix implementations of <tt><font size=+1>/dev/fd</font></tt>, Unix’s dup device.
|
|
If a Unix domain socket is open as file descriptor 0, some implementations
|
|
disallow the opening of <tt><font size=+1>/dev/fd/0</font></tt>; instead one must <a href="../man2/connect.html"><i>connect</i>(2)</a>
|
|
to it. If this functionality is important
|
|
(as it is for <a href="../man1/rc.html"><i>rc</i>(1)</a>), one must <tt><font size=+1>#undef pipe</font></tt> and fall back on the
|
|
(possibly unidirectional) Unix pipes.<br>
|
|
|
|
</table>
|
|
|
|
<td width=20>
|
|
<tr height=20><td>
|
|
</table>
|
|
<!-- TRAILER -->
|
|
<table border=0 cellpadding=0 cellspacing=0 width=100%>
|
|
<tr height=15><td width=10><td><td width=10>
|
|
<tr><td><td>
|
|
<center>
|
|
<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a>
|
|
</center>
|
|
</table>
|
|
<!-- TRAILER -->
|
|
</body></html>
|