MATLAB: Does Matlab system call wait for the operation to finish before continuing with the script

external commandlinuxsystemunix

I have a script where I am making system calls such as:

cmd = 'tar -xvf filename.tar';
system(cmd);

My question is, once Matlab has started the system call, does it continue on with the Matlab script immediately or does it wait for the system call to finish outside Matlab before continuing on with the script?

Thanks in advance! James

Best Answer

It waits for the process. However if the process starts a subprocess and then exits, it will not wait for the subprocess. So if you do not want it to wait, add " &" to the end of the command.

cmd = 'tar -xvf filename.tar &';

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MATLAB: How to initiate a linux (shell) command from matlab but not wait for the output

If you end the command line with an ampersand, system should return immediately

 system('some-long-running-command &');

Of course, you won't be able to capture the output of the command.

MATLAB: Finishing a calculation

As far as MATLAB is concerned, it has finished the calculations. It has given you exact analytic solutions, rather than mere 16 digit floating point approximations.

I notice that your outputs are complex valued. You need to take extra steps to output complex values properly.

dd = double(d);
fprintf(fid,'%+5.5f %+5.5fi\n', [real(dd(:)), imag(dd(:))].' );

Here the "i" after the "%+5.5f" is just a literal character to indicate the imaginary component.

In the example above it appears that the imaginary component vanishes in practice, which is not at all obvious from casual examination. If that is the situation for all values, then you could use

fprintf(fid,'%+5.5f\n', real(dd(:)) );

but unless you can prove that the imaginaries will vanish, outputting them would be safer.

Best Answer

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MATLAB: Finishing a calculation

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