42 lines
1.6 KiB
Plaintext
42 lines
1.6 KiB
Plaintext
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# What should happen if non-interactive shell gets SIGINT?
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(sleep 1; echo Sending SIGINT to main shell PID; exec kill -INT $$) &
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# We create a child which exits with 0 even on SIGINT
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# (The complex command is necessary only if SIGINT is generated by ^C,
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# in this testcase even bare "sleep 2" would do because
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# in the testcase we don't send SIGINT *to the child*...)
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$THIS_SH -c 'trap "exit 0" SIGINT; sleep 2'
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# In one second, we (main shell) get SIGINT here.
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# The question is whether we should, or should not, exit.
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# bash will not stop here. It will execute next command(s).
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# The rationale for this is described here:
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# http://www.cons.org/cracauer/sigint.html
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#
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# Basically, bash will not exit on SIGINT immediately if it waits
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# for a child. It will wait for the child to exit.
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# If child exits NOT by dying on SIGINT, then bash will not exit.
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#
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# The idea is that the following script:
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# | emacs file.txt
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# | more cmds
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# User may use ^C to interrupt editor's ops like search. But then
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# emacs exits normally. User expects that script doesn't stop.
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#
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# This is a nice idea, but detecting "did process really exit
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# with SIGINT?" is racy. Consider:
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# | bash -c 'while true; do /bin/true; done'
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# When ^C is pressed while bash waits for /bin/true to exit,
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# it may happen that /bin/true exits with exitcode 0 before
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# ^C is delivered to it as SIGINT. bash will see SIGINT, then
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# it will see that child exited with 0, and bash will NOT EXIT.
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# Therefore we do not implement bash behavior.
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# I'd say that emacs need to put itself into a separate pgrp
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# to isolate shell from getting stray SIGINTs from ^C.
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echo Next command after SIGINT was executed
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