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Re: Executing shell code on the signal stack, or why is this is a bad id

From: Chet Ramey
Subject: Re: Executing shell code on the signal stack, or why is this is a bad idea
Date: Fri, 07 Jun 2013 16:50:32 -0400
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On 6/6/13 5:29 AM, Lionel Cons wrote:
> Forwarding an interesting posting from Roland Mainz who did an
> investigation why signal trap processing in ksh93, bash and dash is
> currently not reliable.

As I said in a previous message, I have done considerable work between
bash-4.2 and bash-4.3 to move signal processing out of signal handlers.
This includes running trap commands.

The only signal for which bash (and other shells) make a guarantee to
execute one instance of a trap for each signal received is SICHLD, and
even in that case the guarantee is not exact: the shell will run the
trap once for each child that exits.

Read the thread beginning at


for a discussion that kicked off some of the work.


``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/

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