How can I send output from MATLAB to the 'stdin' of another program?

How can I send output from MATLAB to the 'stdin' of another program?

Answer 1

[MathWorks Support Team]

There are two options for sending output from MATLAB to the stdin of another program:

File-based Input/Output

Use a combination of MATLAB and your system's command line to accomplish your desired workflow. 

1. Generate the input for the external program in MATLAB and write it to a file:

 

>> f = fopen('programInput.txt');
>> fwrite(f, '...');
>> fclose(f);

2. Use the '!' operator (or the 'system' command) to run a shell command to read the file, pipe the file contents to the programs stdin, and write the program stdout to a file.

Windows:

>> !type programInput.txt | myprogram > output.txt

Linux/Mac:

>> !cat programInput.txt | myprogram > output.txt

If you need to process the output of the program in MATLAB you can read the 'output.txt' file into MATLAB.

Use MATLAB support for Python or Java

MATLAB provides support for calling Python and Java libraries from within MATLAB. It is possible to start a process using Python or Java and manipulate the stdin / stdout of the process within MATLAB. Refer to the documentation for Java's ProcessBuilder or Python's subprocess.Popen.

For more information about MATLAB support for Python, refer to the following links:

https://www.mathworks.com/help/matlab/call-python-libraries.html

For more information about MATLAB support for Java, refer to the following links:

https://www.mathworks.com/help/matlab/using-java-libraries-in-matlab.html

[Frank Wiedmann]

We have implemented a solution for this by using Java, see https://community.cadence.com/cadence_technology_forums/f/mixed-signal-design/37406/communicating-with-the-ncsim-shell-interface-from-matlab-or-octave. I have attached the presentation slides, so that you don't need to register with Cadence. Most interesting for general use are slides 5, 6 and 9 (and the last item of slide 10 if you want to use this solution).