Holding matlab execution while dos/system command is running

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olu 2014-4-20

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https://ww2.mathworks.cn/matlabcentral/answers/126478-holding-matlab-execution-while-dos-system-command-is-running

评论： Theodore Bantounas 2020-11-12

Hi all,

Z (see code below) is a batch file to be executed using 'dos'. The challenge however is that V requires 'x.log' which is an output files after completely executing the batch file. What I observe is error message saying that the output file do not exist; apparently because the 'x.log' is yet to be generated by the batch file. Please How can I make matlab hold on until after the batch file has been completed so that the x.log file can be available as input to V?

z = dos('x.bat'); v = fileread('x.log')

Thank you in advance.

OlFat

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Answer 1

Image Analyst 2014-4-20

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在 MATLAB Online 中打开

Maybe you can enter a loop until it's created

z = dos('x.bat');
% Wait for file to be created.
maxSecondsToWait = 100; % Wait 100 seconds at most.
secondsWaitedSoFar  = 0;
while secondsWaitedSoFar < maxSecondsToWait 
  if exist('x.log', 'file')
    break;
  end
  pause(1); % Wait 1 second.
  secondsWaitedSoFar = secondsWaitedSoFar + 1;
end
if exist('x.log', 'file')
  v = fileread('x.log')
else
  warningMessage = sprintf('Warning: x.log never got created after waiting %d seconds', secondsWaitedSoFar);
  uiwait(warndlg(warningMessage));
end

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Image Analyst 2020-9-7

在 MATLAB Online 中打开

It will break from the loop as soon as the file is detected - 10 seconds in your example. By the way, instead of exist(), this is how you do it now:

if isfile('x.log')

Theodore Bantounas 2020-11-12

Found the code useful. Thank you Img analyst.

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Answer 2

Walter Roberson 2014-4-20

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dos() does wait for the end of the command. However if the command involves opening up an independent graphics window instead of working in command-line mode, then as far as MS Windows is concerned the .bat is finished. There are tools that can be used to detect whether a process is executing if necessary.