Getting process status

Joe Van Dyk

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Mar 29, 2005, 8:51:59 PM3/29/05

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If I have the id of a process, how can I get a Process::Status object for it?

Thanks,
Joe

Joe Van Dyk

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Mar 29, 2005, 9:15:20 PM3/29/05

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Actually, what I'm trying to do is create an application that will be
able to start, kill, and monitor programs on a bunch of linux
machines.

My initial attempt is using DRb.

I have a Node class that will run on each "node". The Node class will
have methods for starting, killing, and monitoring processes. I have
a NodeProcess object that enscapulates starting, killing, and
returning the status of a process.

I also have a NodeMonitor class that will connect to all the different
Node classes and let the user start/kill different processes on the
Node.

Does my design look ok? I'm having some difficulties correctly
starting a process and getting the status of a currently running or
killed process.

To start a process, I have something like
def start_process
@process_id = fork do
$logger.info "Executing '#{@command} #{@arguments}'"
Kernel.exec "#{@command} #{@arguments}"
end
$logger.info "New process id: #{@process_id}"
end
end
where @command and @arguments are just strings that have been set
already. But I'm getting the process id back of the "sh -c
some_command args" process, not the real process.

And I'm still struggling on how to get the status of my process.

Thanks for your input!

Joe

ES

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Mar 29, 2005, 11:31:41 PM3/29/05

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Joe Van Dyk wrote:
> If I have the id of a process, how can I get a Process::Status object for it?

Calling Process#wait should set $? which is the Status object
for the given pid.

> Thanks,
> Joe

E

--
No-one expects the Solaris POSIX implementation!

Joe Van Dyk

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Mar 30, 2005, 12:15:12 AM3/30/05

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On Wed, 30 Mar 2005 13:31:41 +0900, ES <rub...@magical-cat.org> wrote:
> Joe Van Dyk wrote:
> > If I have the id of a process, how can I get a Process::Status object for it?
>
> Calling Process#wait should set $? which is the Status object
> for the given pid.
>

That's not quite what I asked for. I have the pid of a specific
process and I need to find out its status (whether or not it's running
or not).

leon breedt

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Mar 30, 2005, 1:13:19 AM3/30/05

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On Wed, 30 Mar 2005 14:15:12 +0900, Joe Van Dyk <joev...@gmail.com> wrote:
> That's not quite what I asked for. I have the pid of a specific
> process and I need to find out its status (whether or not it's running
> or not).

On Linux at least, you can send signal 0 to determine whether a
process is running or not.

Process#kill(0, 2323)

Over here, I get an Errno::ESRCH exception raised if the process is not running.

Leon

Berger, Daniel

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Mar 30, 2005, 9:42:36 AM3/30/05

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> -----Original Message-----
> From: leon breedt [mailto:bit...@gmail.com]
> Sent: Tuesday, March 29, 2005 11:13 PM
> To: ruby-talk ML
> Subject: Re: Getting process status
>
>
> On Wed, 30 Mar 2005 14:15:12 +0900, Joe Van Dyk
> <joev...@gmail.com> wrote:
> > That's not quite what I asked for. I have the pid of a specific
> > process and I need to find out its status (whether or not
> it's running
> > or not).
> On Linux at least, you can send signal 0 to determine whether
> a process is running or not.

It works on all platforms, including Windows (with Ruby 1.8.x).

Regards,

Dan