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Re: why cant i kill processes?


Kill, by default, send SIGTERM (code 2) to the targeted process.   The
default behavior for such signal is to terminate the process ("man 1
kill" at the prompt). However, processes can defaine a signal handler to
process SIGTERM to do whatever you want it to.  In this case the process
will not terminate but resumed in the point where it was when the
handler was called.

Alternatively you may specify the code of the signal you want to send to
the process, such as in "kill -9 <pid>" or "kill -KILL <pid>".  SIGKILL
cannot be handled by processes, and the default (and only) behavior is
to terminate the process.  This is the "brute force" method., as no
cleanup handler will be called.

However, it looks like that, sometimes, some processes won't die with
SIGKILL!  I guess these processes are blocked somewhere "inside" OS
code, and they won't die until they are resumed by the OS.  But due to
some bug somewhere, they will never be resumed.  The only solution I
know for such a situation is to reboot the machine.  This happens more
frequently with buggy device drivers.  You may always try to find (and
compile) a newer version of teh DD in the hope that the bug(s) annoying
you are already corrected.  Then you will get annoyed by some new
bugs!  ;-)


Joao Lourenco                  Tels: (+351) 212 948 536
Dep. Informatica                     (+351) 212 948 300
FCT / Univ. Nova de Lisboa      Ext: 10740
Quinta da Torre                 Fax: (+351) 212 948 541
P-2829-516 CAPARICA   http://www-asc.di.fct.unl.pt/~jml

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