[SATLUG] Firefox 3.0.1 issue

Bruce Dubbs bruce.dubbs at gmail.com
Sun Aug 24 14:24:27 CDT 2008


Geoff wrote:

> Ah, ok.  the thunderbird binary is still active.  I want to kill it.
> 
>> kill 6425
> 
> if I run ps -ef | grep -i thunderbird again, and the simple kill command
> didn't work, then I issue the;
> 
> kill -s 9 6425
> 
> 9 times out of 10, that -will- kill the process.

It will be helpful to explain what the kill program does.  First of all, 'kill' 
is misnamed.  It should be named 'signal', because thats what it does: sends 
signals to a process or the operating system.

The default signal for kill is TERM, for terminate.  That signal is sent to the 
process to do what the process wants.  The process can intercept the signal and 
decide what to do, including ignoring the signal.  If the process is hung and 
not even looking at signals, nothing will happen.  If a process is not handling 
signals and is not hung, then glibc will intercept the signal on behalf of the 
process and terminate it.

The KILL signal ( -9 ) on the other hand, cannot be caught.  It is handled by 
the operating system, not the process.  The operating system will then terminate 
the program.  By default, the keyboard sends a signal to a process with a CTRL-C 
or CTRL-X

You can send other signals to a process for other activities like rereading a 
configuration file or dumping some data to a file.  It all depeneds on the 
process.  For a list of signals, see `man kill` and `man 7 signal`.

   -- Bruce


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