How do I hold a file open (locked) from a Windows command-line shell script?

Question

I have been reading this thread about detecting a locked file, and now I would like to implement it in my scripts, so I will need a way to programatically detect it in Windows shell scripting.
The accepted solution gives a way to hold a file open/locked:

    (
      >&2 pause
    ) >> test.txt

but this solution needs a key pressing.
I would like to create a Windows shell script similar, like this:

[Create and locking of c:\Temp\ProgramRunning.lck]
--------------- Rest of the Script ---------------
[Blah blah blah]
---------- End of the Main Body the Script ----------
[Unlocking and deletion of c:\Temp\ProgramRunning.lck]

So, when the scripts finishes, the lock file gets deleted (and unlocked, of course). If this script gets stopped, Ctrl+C, window closed, hanging of the system or whatever, the lockfile is not deleted, but is unlocked.

How could I do that?

Harry Johnston · Accepted Answer · 2014-03-23T22:26:34.777

3

You can use call combined with output redirection to hold a file open until the call returns:

call :main 3>myopenfile.txt
goto :eof

:main
rem do whatever here
goto :eof

If needed, you can write to the file from within the call like this:

>>&3 echo hi

edited Mar 23 '14 at 22:26

answered Mar 23 '14 at 22:06

Harry Johnston

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An ellegant idea, @HarryJohnston. What is the meaning of that *"3"*? – Sopalajo de Arrierez Mar 23 '14 at 22:15
1

The stream number: 0 is the input, 1 is standard output, 2 is standard error; 3 through 9 are available for the user. (Note that these extra streams are a feature of cmd.exe and are not available to other applications.) – Harry Johnston Mar 23 '14 at 22:18
The `>>&3 echo hi` idea is great: very useful for things like time stamps. Thanks, @HarryJohnston. – Sopalajo de Arrierez Mar 23 '14 at 22:39

How do I hold a file open (locked) from a Windows command-line shell script?

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