Missing something in the linux terminal after launching matlab from the command line

Question

I'm having a weird behaviour when launching matlab from the command line in linux.

I've a bash script in linux that execute a function in matlab from the command line and does other operations with custom functions written in C++ as follows:

#!/bin/bash
# prepare input data just to be sure it has not been written by other test!
matlab2011a -nodesktop -nosplash -r "prepare_data_matlab( 'A' ); quit"
# launch C++ program
...
# prepare more data
matlab2011a -nodesktop -nosplash -r "prepare_data_matlab( 'B' ); quit"

When the script is finished I can not see what I'm writing in the terminal, although the commands have effects. I need to reset the terminal.

The fact is that everything works fine if I only launch matlab with the prepare_data_matlab( 'A' ) but the problem comes when I execute the function with option prepare_data_matlab( 'B' ).

I have commented line by line and found that the problem is with option B that call the function

dlmwrite(file_name, B, ' ');

which is not used in prepare_data_matlab( 'A' ).

So, how should I execute the matlab from the command line to avoid this behaviour? Is there a known bug with the dlmwrite() function?

I'm using Ubuntu 12.04 64 bits, GNU bash, versión 4.2.24(1)-release (x86_64-pc-linux-gnu) and matlab2011a.

EDITED: The output generated for prepare_data_matlab( 'A' ) is

The output generated for prepare_data_matlab( 'B' ) is

EDITED: file_name is created as strcat(path_to_data,f); where path_to_data = /tmp/ and f = data_out.txt. Matrix B is not displayed before or after.

The only output to the terminal before or after the MATLAB script is generated from the bash script as follow:

echo "#### SELECT DATA FROM WORKSPACE ####"
matlab2011a -nodesktop -nosplash -r "prepare_data_matlab( 'B' ); quit";
echo "#### Process Data as input in a C++ programs ####"

The MATLAB function select data from the workscape and save it to disk as follows:

function [ ] = prepare_data_matlab( type )
if strcmp(type,'A')
    % load data from workscape
    load ('workspace_with_my_arrays.mat', 'A');    
    % save data as a standalone variable
    save('/tmp/A.mat', 'A');
elseif strcmp(type,'B')
    % load data from workscape
    load ('workspace_with_my_arrays.mat', 'B');    
    path_to_data = '/tmp/';
    f            = 'data_out.txt';
    file_name    = strcat(path_to_data,f);
    % save data as a txt file
    dlmwrite(file_name, B, ' ');
end
end

EDITED: whos -file workspace_with_my_arrays.mat

Name                             Size                     Bytes  Class     Attributes

A                             610x340x103            170897600  double              
B                             610x340x103            170897600  double
P                             610x340                  1659200  double              
t1                            38855x100                 31084000  double              
t2                            3921x2x100                6273600  double

There are more arrays in the workspace but those are which I load.

The prepare_data_matlab function is the same as posted above but with an argument error checking as follow:

%% Load data from file 
% Data is saved in a MATLAB variable or in TXT 
if nargin ~= 1
    error('Use: prepare_data_matlab( [ A | B ] )')
end

and the following command:

cd /data/matlab;

which is executed after the arguments error check in both cases (option Aand option B), that is, before the if statement.

Answer 1

The problem is not with dlmwrite. This seems to be a bug in some versions of MATLAB, as reported in this link.

The proposed solution (if you have a buggy version of MATLAB) is to use nohup:

nohup matlab -nodesktop -nosplash -r ...........

UPDATE: Per @Amro 's suggestion, @pQB reported the problem to MathWorks Support. Their response was:

The problem is a known issue in versions prior to R2012a. Run MATLAB under a different shell. For example, neither tcsh or zsh have this issue.

OLD answer: The problem is not with dlmwrite, but with the content of your matrix. Furthermore, unless file_name points to stdout (e.g., file_name='/dev/stdout';), the dlmwrite function will not write anything to screen and will not mess your terminal. Either file_name points to stdout or you are displaying the matrix B right before (or after) the dlmwrite call.

In any case, the problem is with the contents of your matrix B (see the strange characters in your output). You need to fix the problem with your matrix B. Perhaps the method you are using to read its input data is faulty.

Answer 2

If you want to ignore output from MATLAB (like the banner printed at the beginning), launch the process and redirect both the standard input and error to /dev/null device:

#!/bin/sh

echo '### running MATLAB ###'
matlab -nodesktop -nosplash -r "..." > /dev/null 2>&1
echo '### done ###'

./other_script.sh

matlab -nodesktop -nosplash -r "..." > /dev/null 2>&1

Note that you should be careful since MATLAB process returns immediately possibly before it has finished running, which could cause problems if your next program depends on files produced by MATLAB. See here for a possible solution.