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Aucbvax.2761 fa.unix-wizards utzoo!decvax!ucbvax!unix-wizards Thu Aug 20 01:02:49 1981 TTY problem (final word) >From JNC@MIT-XX Thu Aug 20 00:54:35 1981 Well, the final word on what to do with this seems to depend on what you want to have happen to child processes when the top-level process logs out, and what to do with new processes when there's already a tree attached to the TTY. There are several semi-orthagonal issues:

1) Should the children can receive a hangup signal? 2) Should they remain attached to the terminal for signals? 3) Should new processes that get created and open the TTY become attached to the pgrp?

I guess my answer is no to the first two, which leads to the code I suggested, but if I answer yes to the third the code in tty becomes:

if (p->pgrp == 0) { if (tp->t_pgrp == 0) tp->t_pgrp = p->p_pid; p->p_pgrp = tp->t_pgrp; }

Whether you smash tp->t_pgrp back to zero in sys1 depends on your answer to question 2; if you decide the answer is no you do, but then you more or less have to answer 3 yes, otherwise gross lossage ensues with new shells when old processes are still active. You can attempt to win by smashing tp->t_pgrp to zero in tty, but this doesn't really win. I count that as useless code. I hope this recitation isn't too confusing; as far as I can tell it is 'the right thing'. To answer question 1 the other way around (which Berkeley does) you need support to do the right thing, which 4BSD has. Thanks to Tom Texeira (TJT) for digging out the code fragmemnt above. Noel -------

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