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Re: CVS commit: src/usr.bin/pkill

On Nov 21, 2012, at 1:25 PM, Christos Zoulas wrote:

> In article <>,
> David Laight  <> wrote:
>> On Wed, Nov 21, 2012 at 12:43:20PM -0500, Christos Zoulas wrote:
>>> On Nov 22,  4:39am, (matthew green) wrote:
>>> -- Subject: re: CVS commit: src/usr.bin/pkill
>>> | this seems like a fairly big semantic change to me.
>>> | 
>>> | could you change it to take a new option to look in argv[0] instead
>>> | of p_comm?  p_comm is not changeable by the user.
>>> You could already do this with -f. The point was to make the default case
>>> behave intuitively. Adding an option is against that. I could add backwards
>>> compatibility by checking both, but I think that in the long term this will
>>> be dangerous and confusing (since you might end up killing more than you
>>> thought you would...)
>> That (killing too much) is always true when you use something like pkill().
>> At least it is better that the 'ps | grep' I've seen many people do!
> Yes, this is why it is best to not use things that kill by name from scripts.
>> Is pkill() guaranteed to do an atomic traversal of the process list?
>> So it will kill something that keeps using fork() to change its pid.
> I don't think our libkvm offers that.

How could you guarantee this short of moving this into the kernel so you could 
do all the comparisons while keeping all forks from happening?


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