Try, Catch not working with system command.

In my program I have the following block of code,

try
    !"C:\Program Files\MATLAB\R2016b\bin\matlab.exe" -r "foo"
catch
    warning('Directory was not found. Please locate the MATLAB R2016b installation.');
    [f2016, d2016] = uigetfile('*.exe','Locate MATLAB R2016b Executable');
    cmd = strcat('!"',d2016,f2016,'" -r "foo"');
    eval(cmd);
end

When I run it normally, everything works fine. But when I alter the path in try to create an error, the catch is never executed. Instead the program terminates and I'm left with "The system cannot find the path specified". This text isn't displayed as an error which is probably the issue, but is there any way to make my try, catch work? Or at least a workaround?

Answer 1

[Walter Roberson]

I recommend converting to use system()

path_to_matlab = '"C:\Program Files\MATLAB\R2016b\bin\matlab.exe"';

try_again = true;
while try_again

    try
        cmd = sprintf('"%s" -r "foo"', path_to_matlab);
        [status, result] = system(cmd);
        if status == 0; try_again = false; end
    catch ME
    end

    if try_again
        warning('MATLAB was not found. Please locate the MATLAB R2016b installation.');
        [f2016, d2016] = uigetfile('*.exe','Locate MATLAB R2016b Executable');
        if isnumeric(f2016)
          fprintf('Canceling');
          break
        end
        path_to_matlab = fullfile(d2016, f2016);
    end
  end

It is not clear why you are starting a new MATLAB session ?

You should consider using

if ispc()
   path_to_matlab = fullfile(matlabroot, 'bin', 'matlab.exe');
   file_select_ext = '*.exe');
else
   path_to_matlab = fullfile(matlabroot, 'bin', 'matlab');
   file_select_ext = '*');
end

try_again = true;
while try_again

    try
        cmd = sprintf('"%s" -r "foo"', path_to_matlab);
        [status, result] = system(cmd);
        if status == 0; try_again = false; end
    catch ME
    end

    if try_again
        warning('MATLAB was not found. Please locate the MATLAB R2016b installation.');
        [f2016, d2016] = uigetfile(file_select_ext, 'Locate MATLAB R2016b Executable');
        if isnumeric(f2016)
          fprintf('Canceling');
          break
        end
        path_to_matlab = fullfile(d2016, f2016);
    end
  end

[Adam Hicks]

I'm running MATLAB R2010b due to functionality that hasn't been updated for newer versions yet. However, the final step of my program requires functionality that only exists in newer versions of MATLAB, hence why I am calling 'foo' in a new MATLAB instance.

Answer 2

[Fangjun Jiang]

use system() to replace the "!" to call your program.

[status,result] = system('command')

Use the returned "status" to determine your next step.