*Thanks Rob.* Yes, the backslash \ is a character that escapes the
following character. I used backslashes historically but will try forward
slashes with my current modern installation.
*Fred, that's brilliant !!!!!!*
exec("cmd /c start \"\" build.bat");
Solves my problem ! I had already tried that, but without the double ""
(escaped) which opens a new *persistent *untitled cmd window. My previous
attempt, based on the examples in
https://wsr.imagej.net/macros/ExecExamples.txt also opened a new cmd window
but closed it immediately, and perhaps that was the problem. I use print()
to check the strings I pass to exec().
*Now, to be tidy, I just need to close that cmd window, after perhaps
waiting a moment. *But I'm very happy that I can finally launch SharpCap
with Python scripting from an imageJ script.
Thanks also for the explanation of how exec() works. It was probably quite
difficult to implement, having to pass parameters through several systems.
It's perhaps still not quite perfect, which to my mind would mean that
anything that worked in a Windows cmd shell or .bat file worked in exec,
and that exec itself would parse the string. At least, the stated exec()
requirement to use comma separated arguments when there are spaces in the
cmd string, like
exec("cmd", "/c", "start", "excel.exe", path);
no longer seems necessary.
Thanks again to all who responded, suggested new ideas, and solved my
problem. Alan.
On Tue, 10 Feb 2026 at 06:26, Fred Damen <[email protected]> wrote:
> Greetings,
>
> A slightly more complicated explanation...
>
> ImageJ's macro function exec passes its parameters to JVM, which passes
> its parameters to posix system call, which requests the OS to execute an
> executable. At each stage things are manipulated. System shell commands
> are not actually executables. You need to pass your shell command (.bat)
> to an executable (cmd) to execute it.
> exec("cmd /c start \"\" build.bat");
> see:
>
> https://stackoverflow.com/questions/615948/how-do-i-run-a-batch-file-from-my-java-application
> second answer.
>
> If you want to try and figure out what is going on and resolve the issue,
> try and execute the 'echo' command with your command as its parameters;
> echo simply displays its parameters. This will be frustrating and
> enlightening, although it may help...
>
>
> Fred
>
> On Mon, February 9, 2026 9:50 am, Alan Hewat wrote:
> > Thanks Fred.
> >
> > Unfortunately *ImageJ exec() doesn't run Windows .bat files as expected
> > either :-(*
> >
> > I have a simple .bat file containing one line, that *executes without
> > error
> > when I double-click it in Windows*
> > "C:\Program Files\SharpCap 4.1 (64 bit)\SharpCap.exe" /language=fr
> > It launches SharpCap <https://docs.sharpcap.co.uk/4.1/>, a popular
> imaging
> > application for astronomers, with a command-line argument that specifies
> > the language
> >
> > If instead I execute it within an imageJ script with
> > status = exec("C:\Program Files\SharpCap 4.1 (64 bit)\SharpCap.exe"
> > /language=fr);
> > It launches SharpCap but the in-line argument disables SharpCap's own
> > IronPython script with a "codepage___0" error.
> > (It does work without the in-line argument, and I want to input more
> > complicated arguments than the trivial /language).
> >
> > Other users have reported similar problems and it was suggested
> > <https://forums.sharpcap.co.uk/viewtopic.php?t=6762>that the code page
> or
> > environment variables may be set differently.
> > This problem occurs however I try to execute SharpCap with exec(), e.g.
> > https://wsr.imagej.net/macros/ExecExamples.txt
> > There is a nice example
> > <https://imagej.net/ij/macros/tools/VideoCaptureTool.txt> of using
> exec()
> > with command-line arguments to record and playback VirtualDub video
> > That works for me, but doesn't help me understand my problem.
> >
> > *So is there any other way of launching a Windows process from an imageJ
> > macro other than exec() ?*
> >
> > Regards, Alan.
> >
> > On Mon, 9 Feb 2026 at 05:45, Fred Damen <[email protected]> wrote:
> >
> >> Greetings,
> >>
> >> Generally when I need to run a command line program from within a
> >> program
> >> I am writing and the passing of arguments becomes to frustrating (as
> >> there
> >> are many layers of retranslating the command syntax), I write a command
> >> line command in the OS(es) native macro language, .bat/.cmd in your
> >> case.
> >> Then the only thing that I need to get correct in the calling program is
> >> executing the OS macro command itself - which you seem to have
> >> accomplished.
> >>
> >> Enjoy,
> >>
> >> Fred
> >>
> >>
> >> On Sun, February 8, 2026 3:22 am, Alan Hewat wrote:
> >> > SharpCap <https://docs.sharpcap.co.uk/4.1/> is a popular astronomical
> >> > imaging application and can be launched from a Windows cmd shell with
> >> > a command-line
> >> > argument
> >> <https://docs.sharpcap.co.uk/4.0/34_CommandLineArguments.htm>,
> >> > like this:
> >> > C:\Users\alanh>"..\\..\\Program Files\\SharpCap 4.1 (64
> >> > bit)\\SharpCap.exe"
> >> > /runscript d:\\cameraList.py
> >> > This correctly launches SharpCap to run a Python script cameraList.py
> >> to
> >> > list available cameras (or whatever else is requested).
> >> >
> >> > ImageJ has an exec() function
> >> > <https://wsr.imagej.net/developer/macro/functions.html#E> that can be
> >> used
> >> > to launch applications from an imageJ script. The following launches
> >> > SharpCap, but apparently doesn't pass the /runscript argument
> >> correctly
> >> > because SharpCap scripting reports an error and doesn't work.
> >> > SharpCap = getDirectory("startup")+"..\\..\\Program Files\\SharpCap
> >> 4.1
> >> > (64
> >> > bit)\\SharpCap.exe";
> >> > status=exec (SharpCap+" /runscript d:\\cameraList.py");
> >> >
> >> > Guided by the exec() function
> >> > <https://imagej.net/ij/macros/ExecExamples.txt> examples, I tried
> >> instead:
> >> > status=exec("cmd", "/c", "start", SharpCap, " /runscript", "
> >> > d:\\cameraList.py" );
> >> > but an error that "*Windows can't find /runscript*" is returned as if
> >> it
> >> > thinks */runscript* is an application.
> >> > Replacing */runscript* with the application *SharpCap* as below works,
> >> but
> >> > I don't understand why
> >> > status=exec("cmd", "/c", "start", SharpCap, SharpCap, " /runscript", "
> >> > d:\\cameraList.py" );
> >> > That launches SharpCap, and no error is reported, but the script is
> >> not
> >> > executed.
> >> >
> >> > *The last attempt seems to be close to working, but I must have made
> >> some
> >> > mistake in the exec() syntax.*
> >> >
> >> > The latest versions of imageJ and Win-11 were used. Any suggestions
> >> would
> >> > be appreciated. Alan.
> >> >
> >> >
> >> > --
> >> > *_______________________________*
> >> > Dr Alan Hewat, NeutronOptics
> >> > Grenoble, FRANCE (from computer)
> >> > [email protected]
> >> > +33.476984168 VAT:FR79499450856
> >> > http://NeutronOptics.com/hewat <http://neutronoptics.com/hewat>
> >> > _______________________________
> >> >
> >> > --
> >> > ImageJ mailing list: http://imagej.nih.gov/ij/list.html
> >> >
> >>
> >> --
> >> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
> >>
> >
> >
> > --
> > *_______________________________*
> > Dr Alan Hewat, NeutronOptics
> > Grenoble, FRANCE (from computer)
> > [email protected]
> > +33.476984168 VAT:FR79499450856
> > http://NeutronOptics.com/hewat <http://neutronoptics.com/hewat>
> > _______________________________
> >
> > --
> > ImageJ mailing list: http://imagej.nih.gov/ij/list.html
> >
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>
--
*_______________________________*
Dr Alan Hewat, NeutronOptics
Grenoble, FRANCE (from computer)
[email protected]
+33.476984168 VAT:FR79499450856
http://NeutronOptics.com/hewat <http://neutronoptics.com/hewat>
_______________________________
--
ImageJ mailing list: http://imagej.nih.gov/ij/list.html
