1 | # What should happen if non-interactive shell gets SIGINT?
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2 |
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3 | (sleep 1; echo Sending SIGINT to main shell PID; exec kill -INT $$) &
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4 |
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5 | # We create a child which exits with 0 even on SIGINT
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6 | # (The complex command is necessary only if SIGINT is generated by ^C,
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7 | # in this testcase even bare "sleep 2" would do because
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8 | # in the testcase we don't send SIGINT *to the child*...)
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9 | $THIS_SH -c 'trap "exit 0" SIGINT; sleep 2'
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10 |
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11 | # In one second, we (main shell) get SIGINT here.
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12 | # The question is whether we should, or should not, exit.
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13 |
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14 | # bash will not stop here. It will execute next command(s).
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15 |
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16 | # The rationale for this is described here:
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17 | # http://www.cons.org/cracauer/sigint.html
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18 | #
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19 | # Basically, bash will not exit on SIGINT immediately if it waits
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20 | # for a child. It will wait for the child to exit.
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21 | # If child exits NOT by dying on SIGINT, then bash will not exit.
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22 | #
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23 | # The idea is that the following script:
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24 | # | emacs file.txt
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25 | # | more cmds
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26 | # User may use ^C to interrupt editor's ops like search. But then
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27 | # emacs exits normally. User expects that script doesn't stop.
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28 | #
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29 | # This is a nice idea, but detecting "did process really exit
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30 | # with SIGINT?" is racy. Consider:
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31 | # | bash -c 'while true; do /bin/true; done'
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32 | # When ^C is pressed while bash waits for /bin/true to exit,
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33 | # it may happen that /bin/true exits with exitcode 0 before
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34 | # ^C is delivered to it as SIGINT. bash will see SIGINT, then
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35 | # it will see that child exited with 0, and bash will NOT EXIT.
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36 |
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37 | # Therefore we do not implement bash behavior.
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38 | # I'd say that emacs need to put itself into a separate pgrp
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39 | # to isolate shell from getting stray SIGINTs from ^C.
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40 |
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41 | echo Next command after SIGINT was executed
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