On 14/12 23:31, Hendrik Boom wrote: > On Sun, Dec 13, 2020 at 09:31:02PM +0100, Didier Kryn wrote: > > Le 13/12/2020 à 03:15, Steve Litt a écrit : > > > On Fri, 11 Dec 2020 15:53:35 +0100 > > > Didier Kryn <k...@in2p3.fr> wrote: > > > > > > > > >> I don't make it an argument against xdm. Just cheating about your > > >> own arguments (~: > > > Didier, why didn't you make that suggestion to me 15 years ago? It's a > > > brilliant way to guarantee that if somebody logs out of X, they have no > > > logged in shell to make mischief with. > > > > > > I should have thought of that myself. 15 years ago :-). > > > > > Yes you should have. But this is something everybody forgets all the > > time. We all imagine a program invocation like a function call, in which > > the caller is suspended until the callee returns; but actually when the > > shell is suspended waiting the application to return, it intentionnally > > waits, but can easily stop waiting. The artefact is that we must add an > > '&' to tell it not to wait in the first place. This is a semantic sugar > > to make it behave by default "as if" it was a function call. > > > > exec does not create a new process; instead it substitutes the new > > application to the current one (the shell). I had fun some years ago > > writing an application which opened an http connection to a server on > > standard input, read the http header, and then execed another > > application given in argument. > > We Scheme programmers are very aware of this -- it's called tail-calling, and > the Scheme > implementation does this anytime it can.
indeed. And in Forth it's called "next" :) Ralph. _______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
