In the last episode (Jan 28), Julian Elischer said: > Harti Brandt wrote: > >On Fri, 28 Jan 2005, Julian Elischer wrote: > > > >JE>however echo $$ > >JE>and > >JE> ( echo $$ ) > >JE> > >JE>produce the same result. > > > >I think that the $$ is expanded in the old shell in any case. > > hence my test of > ps -l vs (ps -l) > > unfortunatly the shell short circuits that too if it's too simple. I think POSIX is careful to define a "subshell" as "a duplicate of the shell environment [... where] changes made are not visible to the parent shell environment". They don't mention forking processes, which allows shell authors to skip forking a separate shell process if they can determine that there's no need for one. I don't think there's any way for a subshell to determine its own pid if you know it's running in another process, even if it's an asynchronous one. At least the parent knows that pid, though, via $!. -- Dan Nelson dnelson_at_allantgroup.comReceived on Fri Jan 28 2005 - 16:14:36 UTC
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