[Gambas-user] Avoiding multiple instances

[Rolf-Werner Eilert]

Leonardo Miliani schrieb:
> Jeffrey Cobb ha scritto:
>> I've made a small toolbar app to run in fluxbox.  I've included the
>> binary in my xinitrc file.  But I'd like to know how I can avoid
>> multiple instances of the same app running.  How does a gambas program
>> detect another copy of itself running?
>>
>> Jeff
>>
>>
>>
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> 
> I can suggest you how I solved this problem.
> When an application of mine starts, it creates a file just by executing
> this code:
> 
> PRIVATE FUNCTION Check_If_Running() AS Boolean
> DIM TempString AS String
> DIM hFile AS File
>   TempString = Application.Path & "/.running"
>   IF Exist(TempString) THEN
>     Message.Warning("No multiple instances allowed")
>     RETURN TRUE
>   END IF
>   hFile = OPEN TempString FOR CREATE
>   CLOSE #hFile
>   RETURN FALSE
> END
> 
> The first time that the app starts it creates an empty hidden file and
> it returns FALSE because it didn't find another instance running.
> The second time that you call the function you'll get TRUE because the
> program is running (it created the check file).
> Just by checking its existance you can know if another instance of the
> program is running.
> 
> Of course, when you close the app, you have to delete it:
> 
> PUBLIC SUB Form_Close()
> 
>   IF Exist(Application.Path & "/.running") THEN
>     KILL Application.Path & "/.running"
>   END IF
> 
> END
> 

Indeed, that is the problem with this solution: if the app crashes, it 
will prevent itself from being restarted until the user manually deletes 
the hidden file. I didn't find a good way out of this yet :-)

Rolf