Re: SIGINT handling

[Chet Ramey]

On 9/22/15 8:18 AM, Greg Wooledge wrote:
> On Mon, Sep 21, 2015 at 10:07:55PM +0100, Stephane Chazelas wrote:
>> Maybe the test scenario was not clear:
>>
>> bash -c 'cmd; echo hi'
>>
>> is run from an interactive shell, cmd is a long running
>> application (the problem that sparked this discussion was with
>> ping and I showed examples with an inline-script calling sleep)
> 
> Just for the record, ping is the *classic* example of an incorrectly
> written application that traps SIGINT but doesn't kill itself with
> SIGINT afterward.  (This seems to be true on multiple systems -- at
> the very least, HP-UX and Linux pings both suffer from it.)
> 
> A loop like this works as expected:
> 
> while true; do
>   sleep 1
> done
> 
> A loop like this does not:
> 
> while true; do
>   ping -c 1 some.host     # or on HP-UX, ping some.host -n 1
> done

If you decide, as bash has, to allow the foreground job to determine what
to do with SIGINT, you have to cope with software like ping.

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