Re: [Wrapper-user] Getting service status on Unix

[Mark L. <mid...@ve...>]

Leif,

Thanks for your response. I don't know much about Unix shell 
programming, so I didn't check the script. But after reading your post, 
I looked at it, and I think I know enough to say this it does indeed do 
what I was looking for. Probably I didn't explain it very well. I was 
hoping to use the return value from invoking the script with the 
argument "status" to tell whether the service was running. I observed 
that it returns 1 when the script is not running, and 0 otherwise. I 
didn't see this documented, so I wondered if it would always be the 
case. But doesn't the following code from the script mean that this is 
indeed the intended behavior, and I can therefore rely on it?

status() {
    getpid
    if [ "X$pid" = "X" ]
    then
        echo "$APP_LONG_NAME is not running."
        exit 1
    else
        echo "$APP_LONG_NAME is running ($pid)."
        exit 0
    fi
}

I prefer this approach to checking for the presence of the pid file, 
since, as you pointed out, the script ensures not only that a process is 
running with a pid equal to the pid in the pid file, but also that that 
process is the wrapper process.

-Mark

Leif Mortenson wrote:
> Mark,
> The shell script on UNIX does not currently work that way.  It would
> be easy to modify the shell script to do so however when it is called
> with the "status" command.
>
> As an alternative, would checking for the pid file work for you?  The
> Wrapper can be configured to output a pid file on startup.  This is
> the norm when using the provided shell script on UNIX but needs
> to be set on Windows: wrapper.pidfile
>
> You can also check for a running JVM with the wrapper.java.pidfile
> property.
>
> If you want more detail on the exact status of the Wrapper or JVM
> processes, you could also use the wrapper.statusfile and
> wrapper.java.statusfile properties.
>
> See the documentation for all of the above.
> http://wrapper.tanukisoftware.org/doc/english/properties.html
>
> Just so you are aware, the pid file will always be deleted if the
> Wrapper shuts down normally, but it could be left around if the
> Wrapper were to crash or be killed with kill -9.  Same if the OS
> itself were to crash.  The shell script works around these cases
> by actually looking for the process located within the pid file.
>
> Cheers,
> Leif
>
> Mark Leone wrote:
>> I'm using Runtime.exec() Java method to execute the Unix script that 
>> was re-named to the name of my app. Thus I use
>>
>> String[] cmd = new String[]{myPath + "/myAppName" ,"status"};
>> Process process = Runtime.getRuntime().exec(cmd);
>>
>> I can capture the standard output from process, and get a verbal 
>> description of the status of the service. However I'd prefer to get 
>> an integer or byte status, the way it works with Windows (executing 
>> wrapper.exe, not the script). So instead of capturing standard out 
>> from the Process created by exec(), I use
>>
>> int result = process.waitFor();
>>
>> When I do this, result = 1 if the service is not running, 0 if the 
>> service is running. (If I get the status of executing "wrapper -qs 
>> ../conf/wrapper.conf" as with Windows, I get result = 1 no matter if 
>> the service is up or down.) I don't see this status result documented 
>> anywhere for the Unix script. Is this behavior I can rely on, or 
>> should I parse the standard output from process to determine the 
>> status of the service? I'm trying to avoid the latter, because I'm 
>> having trouble processing the standard output from process when I 
>> invoke exec() from the Event Dispatch Thread, which I need to do.
>>
>> -Mark
>>   
>
>
>