Re: $pid

[John (_You_ hide, they seek.) Mackin <john@vetsci.su.oz.au>]

This is not a bug.  Byron thought about this carefully.  Do you really want

	whatis pid

and

	whatis pid >file

to give different pids?  That would be one awful consequence of having $pid
behave in the way some have been suggesting recently.

Now I agree that this is confusing at first, and I will stand 100%
behind any proposal to change rc.1 to explain this more fully.  But
please, _don't_ change the code.

I append the mail Byron sent me when I asked him about this.

OK,
John.

From: Byron Rakitzis <byron@archone.tamu.edu>
Date: Thu, 23 Jan 1992 13:54:56 +1100
To: john@vetsci.su.oz.au
Subject: Re: rc file descriptor bug
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$pid is not EXPORTED. Note that this is much different from saying that a
subshell of rc has $pid wiped out of its hash table. $pid obeys the following
property:

	~ $pid `{echo $pid}

is true. Do you think it should be otherwise? How about another variable,
like $ifs. Do you think that

	~ $ifs `{echo $ifs}

should be different? (assuming for the moment that the ~ command I wrote
is just a convenient way to test the two values)

I guess the easiest way to think of this is to notice that $pid never makes
its way into the envp argument of an execve. Other than that, it is kept
around in rc's data structures.