On 15 May, 15:19, Marco Shaw <marco.shaw@_NO_SPAM_gmail.com> wrote:
> char1iecha1k wrote:
> > On 15 May, 13:54, Oisin Grehan <ois...@gmail.com> wrote:
> >> On May 15, 5:11 am, char1iecha1k <charlesgarg...@gmail.com> wrote:
>
> >>> On 15 May, 09:09, RichS <R...@discussions.microsoft.com> wrote:
> >>>> Is this for reading, writing or both
> >>>> --
> >>>> Richard Siddaway
> >>>> Please note that all scripts are supplied "as is" and with no warranty
> >>>> Blog:http://richardsiddaway.spaces.live.com/
> >>>> PowerShell User Group:http://www.get-psuguk.org.uk
> >>>> "char1iecha1k" wrote:
> >>>>> Hi,
> >>>>> I would like to open a file for exclusive access for the duration of a
> >>>>> script. If the script fails or finishes the lock must be released.
> >>>>> This is to prevent another user or process from accessing the same
> >>>>> data file. I have googled to no avail.
> >>>>> Thanks in advance
> >>> I want to open file for reading, and when open disallow any other
> >>> process from opening that file. So far I have this
> >>> $test1=new-object System.IO.FileStream("test1.txt",
> >>> [System.IO.FileMode]::Open)
> >>> Now I need to know how to return the state of the file into a variable
> >>> so that my script can move on to the next unopen file ie
> >>> for each file in folder open file (if $file already open then return,
> >>> else process job)
> >>> hope that makes sense- Hide quoted text -
> >>> - Show quoted text -
> >> Do you have control of these other scripts? If so, why not use a
> >> traditional ".lock" file - e.g. when you start up, create a file
> >> called "mydatafile.lock," and delete it when you're finished. All
> >> scripts should look for this while on start up, and quit if it already
> >> exists.
>
> > Thats the way I do it at the moment. If the script errors for some
> > unkown reason then the lock file doesnt get removed.
>
> > If I open a file in a script as soon as the script ends (due to an
> > error or natural cause) the file will close.
>
> > I have got a bit further, but there are some peculiarities. Here is
> > the relevant bit of the script :
>
> > &{
> > trap { write-host "error"; exit }
> > $script:test = new-object System.IO.FileStream("file.lck",
> > [System.IO.FileMode]::Open)
> > }
> > write-host "success"
>
> > if the file isnt opened anywhere else then there will be no error in
> > the script block and the file is opened.
> > if the file is opened in another process then creating the new object
> > fails and and the trap handler exits the script.
> > as soon as the script finishes or exits the filestream is closed
>
> > this all works but if you run that piece of code in a test batch file
> > and keep running it then some times it displays an error and sometimes
> > not. here is a sample output below
>
> > 1# gc test.ps1
> > &{
> > trap { write-host "error"; exit }
> > $script:test = new-object System.IO.FileStream("cmdc.lck",
> > [System.IO.FileMode]::Open)
> > }
> > write-host "success"
> > 2# .\test.ps1
> > success
> > 3# .\test.ps1
> > success
> > 4# .\test.ps1
> > success
> > 5# .\test.ps1
> > error
> > 6# .\test.ps1
> > success
> > 7# .\test.ps1
> > error
> > 8# .\test.ps1
> > success
> > 9# .\test.ps1
> > error
> > 10# .\test.ps1
> > success
> > 11# .\test.ps1
> > error
> > 12# .\test.ps1
> > success
> > 13# .\test.ps1
> > success
> > 14# .\test.ps1
> > error
> > 15# .\test.ps1
> > error
>
> Sounds like you need to set your PSH script to continue even if there's
> a failure of any sorts so the lock gets created, then removed even if
> any commands within it fail?
>
> http://blogs.msdn.com/powershell/arc...25/583241.aspx
I don't wont to continue if the file is already open. If the file is
not open then I want to open it.
If after that the script fails or finishes naturally then the I want
the filestream to close, which it does most of the time, but as shown
above sometimes it doesn't work properly. I have executed the script
manually (once every second) to produce the output above. Even when
leaving a good 5 seconds between executions it still sometimes errors.
This shouldn't happen, if it should then I need to know why and how to
avoid it