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| <tr><td width=20><td><b>RFORK(3)</b><td align=right><b>RFORK(3)</b> |
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| <p><font size=+1><b>NAME </b></font><br> |
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| rfork – manipulate process state<br> |
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| <p><font size=+1><b>SYNOPSIS </b></font><br> |
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| <tt><font size=+1>#include <u.h><br> |
| #include <libc.h> |
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| <tt><font size=+1>int rfork(int flags)<br> |
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| <p><font size=+1><b>DESCRIPTION </b></font><br> |
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| <i>Rfork</i> is a partial implementation of the Plan 9 system call. It |
| can be used to manipulate some process state and to create new |
| processes a la <a href="../man2/fork.html"><i>fork</i>(2)</a>. It cannot be used to create shared-memory |
| processes (Plan 9’s <tt><font size=+1>RFMEM</font></tt> flag); for that functionality use <i>proccreate</i> |
| (see <a href="../man3/thread.html"><i>thread</i>(3)</a>). |
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| The <i>flags</i> argument to <i>rfork</i> selects which resources of the invoking |
| process (parent) are shared by the new process (child) or initialized |
| to their default values. <i>Flags</i> is the logical OR of some subset |
| of<br> |
| <tt><font size=+1>RFPROC</font></tt> If set a new process is created; otherwise changes affect |
| the current process.<br> |
| <tt><font size=+1>RFNOWAIT</font></tt> If set, the child process will be dissociated from the |
| parent. Upon exit the child will leave no <tt><font size=+1>Waitmsg</font></tt> (see <a href="../man3/wait.html"><i>wait</i>(3)</a>) |
| for the parent to collect.<br> |
| <tt><font size=+1>RFNOTEG</font></tt> Each process is a member of a group of processes that all |
| receive notes when a note is sent to the group (see <a href="../man3/postnote.html"><i>postnote</i>(3)</a> |
| and <a href="../man2/signal.html"><i>signal</i>(2)</a>). The group of a new process is by default the same |
| as its parent, but if <tt><font size=+1>RFNOTEG</font></tt> is set (regardless of <tt><font size=+1>RFPROC</font></tt>), the |
| process becomes the first in a new group, isolated |
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| from previous processes. In Plan 9, a process can call <tt><font size=+1>rfork(RFNOTEG)</font></tt> |
| and then be sure that it will no longer receive console interrupts |
| or other notes. Unix job-control shells put each command in its |
| own process group and then relay notes to the current foreground |
| command, making the idiom |
| less useful.<br> |
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| <tt><font size=+1>RFFDG</font></tt> If set, the invoker’s file descriptor table (see <i>intro</i>(<i>))</i> |
| is copied; otherwise the two processes share a single table. |
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| File descriptors in a shared file descriptor table are kept open |
| until either they are explicitly closed or all processes sharing |
| the table exit. |
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| If <tt><font size=+1>RFPROC</font></tt> is set, the value returned in the parent process is |
| the process id of the child process; the value returned in the |
| child is zero. Without <tt><font size=+1>RFPROC</font></tt>, the return value is zero. Process |
| ids range from 1 to the maximum integer (<tt><font size=+1>int</font></tt>) value. <i>Rfork</i> will |
| sleep, if necessary, until required process resources are available. |
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| Calling <tt><font size=+1>rfork(RFFDG|RFPROC)</font></tt> is equivalent to calling <a href="../man2/fork.html"><i>fork</i>(2)</a>.<br> |
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| <p><font size=+1><b>SOURCE </b></font><br> |
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| <tt><font size=+1>/usr/local/plan9/src/lib9/rfork.c<br> |
| </font></tt> |
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| <p><font size=+1><b>DIAGNOSTICS </b></font><br> |
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| <i>Rfork</i> sets <i>errstr</i>.<br> |
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