Not same fprintf MATLAB and Linux Console

Hello everybody,

I am trying to catch an error and I have made the following code in Matlab:

catch ME

            % Some error occurred if you get here.
        errorMessage1 = sprintf('Error in function %s()\n',ME.stack.name);
        errorMessage2 = sprintf('Error in line %d\n',ME.stack(1).line);
        errorMessage3 = sprintf('Error %s()\n',ME.message);
        fprintf(2,'-----------------------------\n');
        fprintf(2,'%s\n', errorMessage1);
        fprintf(2,'-----------------------------\n');
        fprintf(2,'%s\n', errorMessage2);
        fprintf(2,'-----------------------------\n');
        fprintf(2,'%s\n', errorMessage3);

The output of Matlab is the following one:

Error in hello()

Error in line 386

Error Index exceeds matrix dimensions.()

But, when I execute matlab from de Linux console:

./matlab < hello.m

I just get this output:

Index exceeds matrix dimensions

I cannot see the line or the .m I am running.

What kind of problem is this?

Thanks in advance,

Javi

Answer 1

[Jan]

If you write the message to stderr by

fprintf(2, '%s\n', errorMessage1);

you have to catch this channel also. Try:

fprintf(1, '%s\n', errorMessage1);

Perhaps this works instead, but I cannot try it currently and hopefully someone corrects me:

matlab -r hello.m 2>&1

[Javier Naranjo]

Can you explain me 2>&1 what exactly does?

I used fprintf(1,..) and it did not work...

[Jan]

But 2>&1 works? I did not work with Linux for 20 years now...

This redirects the stream 2 (stderr) to 1 (stdout). See https://en.wikipedia.org/wiki/Redirection_(computing).

Do you see that I have used "matlab -r hello.m" instead of "matlab < hello.m"?

[Javier Naranjo]

Thanks for your help.

But it seems not to work...

I just get the fprintf of the error, not the line or function

[Jan]

This is not clear: What exactly is "the fprintf of the error"? Do you get any output from stdout? I'm surprised that fprintf(1, ...) does not work.

[Javier Naranjo]

The problem is that when I execute the script in MATLAB and I get an error I can see the 3 fprintf in the console (MATLAB console) (errorMessage1, errorMessage2,...)

On the other hand, when I execute in the Linux Console ./matlab < hello.m and I get an error it does not show any of the errorMessage and I only get for example: Index exceeds matrix dimensions.

I do not see the fprintf of the line or the function.

Thanks for your help

[Jan]

Perhaps this helps: https://de.mathworks.com/matlabcentral/answers/91607-how-can-i-redirect-the-command-window-output-to-stdout-and-stderr-when-running-matlab-7-8-r2009a-i

[Javier Naranjo]

Thanks you so much! It worked! I am running hello.m from another script that opens and closes a diary.

The little problem now is that I get:

    No MATLAB command specified

in the Linux Console when I run:

  sudo ./matlab -r < getOutput.m -nosplash -nodesktop

It seems to be a warning... any idea how to solve this issue?

Thanks again!

[Jan]

Try

./matlab -r getOutput.m -nosplash -nodesktop

without the <

[Javier Naranjo]

If I do not write down "<" and I execute

./matlab -r folder1/getOutput.m -nosplash -nodesktop

It turns:

   not variable or function folder1

and it stays in an infinite loop.

[Jan]

Try to use quotes and provide an absolute path:

./matlab -r "~/folder1/getOutput.m" -nosplash -nodesktop

Or single quotes ' ?

[Javier Naranjo]

/folder1/getOutput.m
 |
Error: Unexpected MATLAB operator.

I tried with single and doble quotes and it did not work.. When I write down double it says too many input arguments.

Thanks

[Jan]

@Javier: Sorry, my mistake.

./matlab -r "cd('~/folder1'); getOutput" -nosplash -nodesktop

The parameter of the -r command must contain a valid Matlab command, not the path of a m-function. You can find more details in the documentation: https://www.mathworks.com/help/matlab/matlab_env/startup-options.html