How do I prevent the command that caused an error being displayed in the command line?

The following issue only occurs in my Matlab R2020b installation under Linux, but not under Windows (R2019a):

When an error occurs, the command that caused the error is displayed in the command line. In the specific case, I'm using the 'unix' command to run a linux executable with an input argument, such as:

[status, result] = unix('./my_executable xyz');

In case 'my_executable' returns an error, the command line displays:

./my_executable xyz: Signal 127

(I don't know where the 'Signal 127' is coming from).

I would like to have this message suppressed. In my Windows installation of Matlab R2019a, this message is not displayed.

What do I have to do?

Answer 1

[Hassaan]

Verify Executable: Before executing the command, ensure the executable exists and has the necessary execution permissions. Use Linux commands (ls -l and chmod +x) to check and set permissions.

Redirect Standard Error: Modify the MATLAB command to redirect standard error output to /dev/null to suppress error messages:

[status, result] = unix('./my_executable xyz 2>/dev/null');

Use Try-Catch Blocks: While this won't suppress the message in the shell, it allows MATLAB to handle errors gracefully:

try
    [status, result] = unix('./my_executable xyz');
    % Handle success
catch ME
    % Handle error within MATLAB
    disp('An error occurred.');
end

To my limited knowledge[Other ways may exist]:

MATLAB Preferences/Configuration: There's no direct MATLAB setting to suppress such messages. The solutions focus on command-level handling and error management within MATLAB scripts.

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Answer 2

[Walter Roberson]

./my_executable xyz: Signal 127

That indicates that ./my_executable could not be found. You are not in the directory you thought you are in (or your executable is named something different; you need to include all file extensions (if any))

[Rainer Huber]

Hi Walter,

Thank you very much for your answer!

Maybe I should have added that the purpose of the executable is to check the presence of a copy protection dongle. When I put in the dongle, no error is reported by the exectutable nor by the calling Matlab code. So, the executable was found. When I remove the dongle, the executable returns an error code, which is intended. But in addition, the command "./my_executable xyz: Signal 127" is displayed in the Matlab command line, as stated before. So, it's o.k. and intended that an error occurs (because the dongle is not found), and I display a correspondig error message to the user (e.g., "Dongle not found"), but I don't want that the command "my_executable xyz" is revealed to the user.

[Walter Roberson]

[status, result] = unix('./my_executable xyz 2>/dev/null');

[Rainer Huber]

Thanks again.

This trick was also suggested by Hassaan. The result is that the Matlab command line now displays

' ./my_executable xyz 2>/dev/null'

So, the 'problem' lies in the Matlab domain.

But I noticed when the Matlab script is encrypted as a p-file, the content of the code line is not revealed anymore. I wanted to pcode the scripts anyway, so the problem is solved.

But thank you anyway for your time and effort!

Best,

Rainer