Messages in this thread | | | From | "Adam J. Richter" <> | Date | Mon, 30 Apr 2001 15:05:30 -0700 | Subject | Re: Patch(?): bash-2.05/jobs.c loses interrupts |
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>> Linux-2.4.4 has a change, for which I must accept blame, >> where fork() runs the child first, reducing unnecessary copy-on-write >> page duplications, because the child will usually promptly do an >> exec(). I understand this is pretty standard in most unixes. >> >> Peter Osterlund noticed an annoying side effect of this, >> which I think is a bash bug. He wrote: >> >> > Another thing is that the bash loop "while true ; do /bin/true ; done" is >> > not possible to interrupt with ctrl-c. >> >> I have reproduced this problem on a single CPU system. >> I also modified my kernel to sometimes run the fork child first >> and sometimes not. In that case, that loop would sometimes >> abort on a control-C and sometimes ignore it, but ignoring it >> would not make the loop less likely to abort on another control-C. >> I'm pretty sure the control-C was being delivered only to the child >> due to a race condition in bash, which may be mandated by posix.
>Did you reconfigure and rebuild bash on your machine running the 2.4 >kernel, or just use a bash binary built on a previous kernel version?
>Bash has an autoconf test that will, if it detects the need to do so, >force the job control code to synchronize between parent and child >when setting up the process group for a new pipeline. It may be the >case that you have to reconfigure and rebuild bash to enable that code.
>Look for PGRP_PIPE in config.h.
Rebuilding bash from pristine 2.05 sources under such a kernel does *not* solve the problem. PGRP_PIPE is undef'ed in the resulting config.h.
Adam J. Richter __ ______________ 4880 Stevens Creek Blvd, Suite 104 adam@yggdrasil.com \ / San Jose, California 95129-1034 +1 408 261-6630 | g g d r a s i l United States of America fax +1 408 261-6631 "Free Software For The Rest Of Us."
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