How to make sure a script is only executed once?

[PGTART]

I made a script that does work nice it does do all kind of stuff
However it gets into problems, when the script is double clicked and executed twice.
I need to make sure only whan script can run at a time, how can i achieve that ?

[michaelslamet]

Pgtart,

check _Singleton function and example

[Morthawt]

In the help file look up the function _Singleton http://www.autoitscript.com/autoit3/docs/libfunctions/_Singleton.htm

Edited September 10, 2013 by Morthawt

[careca]

If that doesn't work, maybe try to write to a ini, say, its running write running = 1, and when it starts,

search that, if 1, exit, without changes, the first/original script writes 0 uppon close.

[BrewManNH]

_Singleton is a safer approach.

[TheSaint]

@careca - that's a very odd thing to say. What do you think _Singleton was designed for? If it didn't work, it would be highly likely the user's fault. Better to get it right in that instance, than muck around using alternatives not as good.

[careca]

I Agree, TheSaint, that was not the right sentence right there. I meant something along the lines of, "if you want, as an alternative."

[Celtic88]

__MUTEX()

MsgBox(0, '','')

Func __MUTEX($SEMAPHORE = "Autoit_a")
    Local $ERROR_ALREADY_EXISTS = 183
    DllCall("kernel32.dll", "int", "CreateSemaphore", "int", 0, "long", 1, "long", 1, "str", $SEMAPHORE)
    Local $LASTERROR = DllCall("kernel32.dll", "int", "GetLastError")
    If $LASTERROR[0] = $ERROR_ALREADY_EXISTS Then Exit
EndFunc   ;==>__MUTEX

[TheSaint]

@Mrbenkali - very nice, but hardly needed compared to the much simpler _Simpleton, and it could do with some explanation.

Is "Autoit_a" the program name or what? I'm presuming it would need to be a more unique indicator.

That may even be the same code that _Simpleton uses?

[PhoenixXL]

That may even be the same code that _Singleton uses?

In accordance to my opinion Semaphore can be preferred over Mutex for avoiding duplication of a process, sincea mutex is costly operation due to protection protocols associated with it. Though a Semaphore could be unlocked by another process, it could be ignored for our case.

More Information Difference : Semaphore and Mutex

Edited September 11, 2013 by PhoenixXL

[BrewManNH]

Using a mutex means that the lock won't be unlocked until the calling process closes or unlocks it, whereas a semaphore can be unlocked by any process. Seeing as how the OP asked for a lock, I'd use a mutex.