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<p>Yes, I'm aware of that particular practice, yet one hesitates to
call it a 'standard'. That being said, I don't think it
unreasonable to use <font size="4"><tt>SIGHUP</tt></font> for
something that is never going to have carrier dropped on it. So
background 'systems' processes would be an obvious candidate.<br>
</p>
<p>'Early' Unix to me means before it got ported off the PDP-7. I
started using it in about 1978, which I believe was in the first
decade of its public release from AT&T. In some ways, it was
a significantly different beast than what you see, today.
However, I didn't start doing systems programming on Unix until
about 1985 when the plug got pulled on 36 bits, first Ultrix, then
Sun. This was until about 1988. Maybe we might call that
'middle' Unix?<br>
</p>
<p>Being a 'purist' in Unix is really a pointless exercise. Vendors
and developers agree on things until they don't agree and when
they need something, it's anybody's guess as to what might get
made into an unofficial standard. You'd be surprised (or not).<br>
</p>
<div class="moz-cite-prefix">I'm not saying it's a bad idea. I'm
saying a Unix 'standard' is whatever an unofficial majority thinks
it is, which may or may not be what others think (say POSIX, for
example). You also see a lot of this in the C library. Timing
functions come to mind.</div>
<div class="moz-cite-prefix"><br>
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<div class="moz-cite-prefix">It's a slippery term and what you think
is a standard today may not be in a decade or two.<br>
</div>
<blockquote type="cite"
cite="mid:35BEE431-7265-441E-B5F9-0ADCA5CF5CB1@comcast.net">
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<hr width="100%" size="2">On 11/18/21 10:59 AM, Paul Koning wrote:<br
class="Apple-interchange-newline">
<br class="Apple-interchange-newline">
Maybe I'm referring to something that doesn't go all the way back
to early Unix. But at least in Linux as far back as I can
remember -- certainly back to late last century -- sending SIGHUP
to a daemon has been the standard way to say "reload your
configuration". In the startup managers, a reload command applied
to a particular daemon's entry acts by sending that signal.
<div class=""><br class="">
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<div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>paul<br
class="">
<div><br class="">
<blockquote type="cite" class="">
<div class="">
<hr width="100%" size="2">On Nov 18, 2021, at 10:50 AM,
Thomas DeBellis <<a
href="mailto:tommytimesharing@gmail.com"
class="moz-txt-link-freetext" moz-do-not-send="true">tommytimesharing@gmail.com</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
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charset=UTF-8" class="">
The statement, "Proper Unix fashion", leaves me somewhat
uncomfortable.<br class="">
<div class="">
<p class="">Since I'm ancient, my understanding of <font
class="" size="4"><tt class="">SIGHUP</tt></font> is
to handle a hangup detected on the controlling
terminal or the death of a controlling process. A
hangup started out meaning dropping carrier on a modem
or DTR on a hardwired line. It came to include a
broken network terminal connection.<br class="">
</p>
<p class="">When I think of how to handle a <font
class="" size="4"><tt class="">SIGHUP</tt></font>, I
usually think of 'gracefully' stopping a process
(I.E., saving the user's work instead of ditching it)
and exiting. If you don't do that, then something
else has to be used to get rid of you, perhaps a <font
class="" size="4"><tt class="">SIGTERM</tt></font>.
The problem is that if somebody wants you gone and you
don't go away, you have a 9 on your hands (<font
class="" size="4"><tt class="">SIGKILL</tt></font>).
Now that data is gone.<br class="">
</p>
<p class="">If you usurp <font class="" size="4"><tt
class="">SIGHUP</tt></font> for such use, then
things like <font class="" size="4"><tt class="">NOHUP</tt></font>
won't do the expected thing. There are certainly
reasons to be <font class="" size="4"
face="monospace">NOHUP</font>'ed. In your superior
breaks, you might not want to disappear so somebody
has a chance to attach a debugger to you to try to
figure out what happened.<br class="">
</p>
<p class="">I think the better thing to do would be
handle a <font class="" size="4"><tt class="">SIGUSR1</tt></font>/<font
class="" size="4"><tt class="">SIGUSR2</tt></font>
to reparse.<br class="">
</p>
<p class="">Of course, "proper" is a very relative term
in Unix. Things change and sometimes get used for no
readily apparent reason, the result being that an
unspoken 'standard' happens. It is not uncommon. For
example, Johnny's DECnet bridge does in fact use <font
class="" size="4"><tt class="">SIGUSR1</tt></font>
to display some information. However, it uses a <font
class="" size="4"><tt class="">SIGHUP</tt></font> to
do a reparse. So maybe that's the best of both
worlds...<br class="">
</p>
<div class="moz-cite-prefix">I've never felt strongly
enough about the matter to suggest <font class=""
size="4"><tt class="">SIGUSR2</tt></font> for a
reparse, but if you want to be a purist, then it
probably should.<br class="">
</div>
<blockquote type="cite"
cite="mid:397CB99E-107B-4CAF-8CAA-447C741BE8F1@comcast.net"
class="">
<hr class="" width="100%" size="2">
<pre class="moz-quote-pre" wrap="">On 11/18/21 9:58 AM, Paul Koning wrote:
In proper Unix fashion it could be triggered by a SIGHUP signal</pre>
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