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| Christopher Spears 2005-10-24, 6:56 pm |
| What is the difference between
kill 1, SIGNAL
and
kill 9, SIGNAL ?
By reading books and talking to people, I figured out
that kill 1 is the HUP (hang up signal) and kill 9 is
the kill signal. Don't they do the same thing (i.e.
terminate a program)? I was told that kill 1 is a
"nicer" way to end a program than kill 9.
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| Wiggins d'Anconia 2005-10-24, 6:56 pm |
| Christopher Spears wrote:
> What is the difference between
>
> kill 1, SIGNAL
>
> and
>
> kill 9, SIGNAL ?
>
> By reading books and talking to people, I figured out
> that kill 1 is the HUP (hang up signal) and kill 9 is
> the kill signal. Don't they do the same thing (i.e.
> terminate a program)? I was told that kill 1 is a
> "nicer" way to end a program than kill 9.
>
>
HUP is a catchable signal. Meaning the program receives notification
that a signal has occurred and which signal. This allows the program to
then act in a certain appropriate manner. For example, HUP is often used
to restart a server application such as Apache. Generally the server
will clear its configuration, re-read its configuration, and then
re-perform any startup like stuffs. The KILL (9) signal is not catchable
and causes an immediate death without proper cleanup. It is usually
reserved for a runaway process that can't be killed with one of the
other catchable kill signals like TERM or QUIT.
perldoc perlipc
For more about signals and their handling in Perl.
man -s 7 signal
For more about Unix/POSIX signals.
http://danconia.org
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| John W. Krahn 2005-10-24, 6:56 pm |
| Christopher Spears wrote:
> What is the difference between
>
> kill 1, SIGNAL
>
> and
>
> kill 9, SIGNAL ?
>
> By reading books and talking to people, I figured out
> that kill 1 is the HUP (hang up signal) and kill 9 is
> the kill signal. Don't they do the same thing (i.e.
> terminate a program)? I was told that kill 1 is a
> "nicer" way to end a program than kill 9.
Actually SIGTERM is the "nicer" way to end a program and if that doesn't work
then use SIGKILL. SIGHUP is usually used to tell a program to reread its
configuration files and start anew.
John
--
use Perl;
program
fulfillment
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