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| <tr><td width=20><td><b>EXITS(3)</b><td align=right><b>EXITS(3)</b> |
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| <br> |
| <p><font size=+1><b>NAME </b></font><br> |
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| exits, _exits, atexit, atexitdont, terminate – terminate process, |
| process cleanup<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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| </font></tt> |
| <tt><font size=+1>void _exits(char *msg)<br> |
| void exits(char *msg)<br> |
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| </font></tt> |
| <tt><font size=+1>int atexit(void(*)(void))<br> |
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| </font></tt> |
| <tt><font size=+1>void atexitdont(void(*)(void))<br> |
| </font></tt> |
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| <p><font size=+1><b>DESCRIPTION </b></font><br> |
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| <i>Exits</i> is the conventional way to terminate a process. <i>_Exits</i> also |
| terminates a process but does not call the registered <i>atexit</i> handlers |
| (<i>q.v.</i>). They can never return. |
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| <i>Msg</i> conventionally includes a brief (maximum length <tt><font size=+1>ERRLEN</font></tt>) explanation |
| of the reason for exiting, or a null pointer or empty string to |
| indicate normal termination. The string is passed to the parent |
| process, prefixed by the name and process id of the exiting process, |
| when the parent does a <a href="../man3/wait.html"><i>wait</i>(3)</a>. |
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| Before calling <i>_exits</i> with <i>msg</i> as an argument, <i>exits</i> calls in |
| reverse order all the functions recorded by <i>atexit</i>. |
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| <i>Atexit</i> records <i>fn</i> as a function to be called by <i>exits</i>. It returns |
| zero if it failed, nonzero otherwise. A typical use is to register |
| a cleanup routine for an I/O package. To simplify programs that |
| fork or share memory, <i>exits</i> only calls those <i>atexit</i>-registered |
| functions that were registered by the same process as that calling |
| <i>exits</i>. |
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| Calling <i>atexit</i> twice (or more) with the same function argument |
| causes <i>exits</i> to invoke the function twice (or more). |
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| There is a limit to the number of exit functions that will be |
| recorded; <i>atexit</i> returns 0 if that limit has been reached. |
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| <i>Atexitdont</i> cancels a previous registration of an exit function.<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/atexit.c<br> |
| /usr/local/plan9/src/lib9/_exits.c<br> |
| </font></tt> |
| </table> |
| <p><font size=+1><b>SEE ALSO </b></font><br> |
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| <a href="../man2/fork.html"><i>fork</i>(2)</a>, <a href="../man3/wait.html"><i>wait</i>(3)</a><br> |
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| </table> |
| <p><font size=+1><b>BUGS </b></font><br> |
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| Because of limitations of Unix, the exit status of a process can |
| only be an 8-bit integer. Exit status 0 is used for empty exit |
| messages, and 1 for non-empty messages. |
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| Exit codes 97 through 99 are used by the thread library to signal |
| internal synchronization errors between the main program and a |
| proxy process that implements backgrounding. |
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| To avoid name conflicts with the underlying system, <i>atexit</i> and |
| <i>atexitdont</i> are preprocessor macros defined as <i>p9atexit</i> and <i>p9atexitdont</i>; |
| see <a href="../man3/intro.html"><i>intro</i>(3)</a>.<br> |
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