Problem with the system command in MATLAB - matlab

I am using the system command in MATLAB as follows (with the current directory being 'scripts'):
[status, result] = system('cd ..\\TxtInOut')
However, invoking the system command does not seem to work. It returns status = 0 and result = ''.
Any suggestions?

If you want to change directories, you should use the CD command. The argument can be either a full path or relative path:
cd('c:\matlab\toolbox'); %# Full path to a directory
cd('scripts'); %# Move to a subdirectory "scripts"
cd('..\TxtInOut'); %# Move up one level, then to directory "TxtInOut"
If you want information about a directory, you should use the DIR command. DIR will return an m-by-1 structure of information for a directory, where m is the number of files and folders in the directory. Again, the argument can be either a full path or relative path:
data = dir('c:\matlab\toolbox'); %# Data for a full path to a directory
data = dir('scripts'); %# Data for a subdirectory "scripts"
NOTE: When working on different platforms (i.e. Windows or UNIX), you will have to pay attention to whether you use the file separator \ or /. You can get the file separator for your platform using the function FILESEP. You can also build your file paths using the function FULLFILE.

Any command executed by "system" is external to MATLAB. A command shell is generated, executes your request, and then returns the result. The 0 result indicates successful completion: the command shell changed its current directory as requested and then returned. (Command shells use non-zero to indicate an error, because there are usually many more ways that a program can fail than succeed.) Unfortunately that only affects the command shell's current directory - see gnovice's answer for how to actually change the directory.

you can use cd, dir, ls, etc directly in matlab without call system functions.

You can also use the underlying operating system commands by preceding them by an exclamation sign.
For instance:
!dir will show you the current directory contents in Windows
!pwd will show you the current directory in Linux/Mac
But calling cd does not change the current directory!

Related

Why can't MATLAB find a script that is on MATLABPATH

I've just created a script file in MATLAB, but can not run it. The name of my script is getEnvFiles.m. When I first tried to run it, I got the following result:
>> getEnvFiles
'getEnvFiles' is not found in the current folder or on the MATLAB path, but exists in:
\\wsl$\ubuntu\home\me
Change the MATLAB current folder or add its folder to the MATLAB path.
So, I added this directory (which is actually the current directory) to the search path, but still got the same result:
>> addpath('\\wsl$\ubuntu\home\me')
>> getEnvFiles
'getEnvFiles' is not found in the current folder or on the MATLAB path, but exists in:
\\wsl$\ubuntu\home\me
Change the MATLAB current folder or add its folder to the MATLAB path.
When I check the path, it looks like this directory is on the path:
>> path
MATLABPATH
\\wsl$\ubuntu\home\me
I can further verify that this directory is my present directory:
>> pwd
ans =
'\\wsl$\ubuntu\home\me'
and that getEnvFiles.m is in this directory:
>> ls
. .emacs.d HarborData
.. .emacs~ RawHarborData
.bash_history .landscape at
.bash_logout .motd_shown getEnvFiles.m
.bashrc .profile test.m
.bashrc~ .sudo_as_admin_successful
.emacs
Is the issue that I'm using wsl (Windows Subsystem for Linux), or do I have some other misunderstanding?
Type rehash and then try running your script again. Even though you have added the new directory to your path, you need to update the path cache so that it knows about the new scripts it can see.
The problem seems to lie in WSL's ability to add new files to the directory. When I create a new script within MATLAB, and try to run it, I get the problem discussed above. However, running already existing files is not a problem. For now, my only solution is to close MATLAB after creating a new script and reopen it. Then, I can run it. Although, oddly, I can't open it in MATLAB's editor.....
This may or may not help, but ...
Sometimes you have to prepend execution with .\ in order to run scripts in PowerShell or from within the command prompt (in Windows, I'm not sure about other operating systems).
I get this error quite often, especially when not in Admin mode.
Does this work?
% Get path of executing script.
filePath = matlab.desktop.editor.getActiveFilename; % Note that this isn't necessarily the same as the output of 'pwd()'.
% Or: filePath = mfilename('fullpath')
% Make sure all nested directories of filePath are on the path, then tell MATLAB where you're working.
addpath( genpath( filePath ) ); % If this fails, try one folder up the tree:
% addpath( genpath( fullfile( filePath, '.' ) );
cd( filePath );
Alternatively, it looks like you might have written and saved the script, and then typed it into the command window to execute. If it's not a special type of script (Function/Class/GUI/etc.) then you can simply click 'Run' in the Editor tab (or the F5 key) and MATLAB should prompt you with a 'Change Folder' option, to which you should acquiesce.
If you're running this script through the WSL terminal, try my suggested code.

MATLAB startup.m ignores cd?

in my startup.m-file I call a script init.m. In this init file I determine the folder containing this file, want to set the current directory to this folder and continue with some other initialization stuff.
But when I start Matlab, the file will be executed, but the cd command seems to be ignored and the directory won't get changed. Does somebody know why? I.e. the matlabpath variable is extended by the subfolders....
startup.m:
run 'D:\FloatingZone\mscrystalgrowth\trunk\MATLAB\FzKameradaten\FzCameraEvaluation\init.m';
init.m
% get path to folder containing this function
folder=mfilename('fullpath');
file=mfilename();
folder=folder(1:end-length(file));
% change folder
cd(folder);
% add subfolder to the top of the MATLAB path
addpath(genpath('Tools'));
MATLAB did exactly what you told it; there's nothing special about the startup scripts.
From the documentation for the run command:
run changes to the folder that contains the script, executes it, and resets back to the original folder. If the script itself changes folders, then run does not revert to the original folder, unless scriptname changes to the folder in which this script resides.
So your cd command didn't actually do anything, run had already changed the directory. And then changed it back, exactly as expected.
I'm not 100% clear on what you want your startup to do. As already pointed out run is working correctly.
Alternative startup.m
if isdeployed == false
cd 'D:\FloatingZone\mscrystalgrowth\trunk\MATLAB\FzKameradaten\FzCameraEvaluation\'
init();
end
function init.m stored in your FzCameraEvaluation\ folder.
function init
addpath ( genpath ( '../Tools' ) );
end
Does that work?

Is it possible to set output directory for triangle program from triangle package?

I see no way to set destination directory or file here: http://www.cs.cmu.edu/~quake/triangle.switch.html
Actually, the program places result file in the same directory, even if current directory is different.
Why? Is ti possible to change?
The output files for the program are generated from the input file names. You can see this from the source code on line 3586
strcpy(b->outnodefilename, b->innodefilename);
...
strcat(b->outnodefilename, ".node");
strcat(b->outelefilename, ".ele");
...
Because of that I don't think there is a way to set the output directory as an option. It seems you will need to manually copy the output files to a different directory
cp output.node your/output/dir/output.node && rm output.node

Running a script in bash

I have a script in one of my application folders.Usually I just cd into that locatin in Unix box and run the script e.g.
UNIX> cd My\Folder\
My\Folder> MyScript
This prints the required result.
I am not sure how do I do this in Bash script.I have done the following
#!/bin/bash
mydir=My\Folder\
cd $mydir
echo $(pwd)
This basically puts me in the right folder to run the required script . But I am not sure how to run the script in the code?
If you can call MyScript (as opposed to ./MyScript), obviously the current directory (".") is part of your PATH. (Which, by the way, isn't a good idea.)
That means you can call MyScript in your script just like that:
#!/bin/bash
mydir=My/Folder/
cd $mydir
echo $(pwd)
MyScript
As I said, ./MyScript would be better (not as ambiguous). See Michael Wild's comment about directory separators.
Generally speaking, Bash considers everything that does not resolve to a builtin keyword (like if, while, do etc.) as a call to an executable or script (*) located somewhere in your PATH. It will check each directory in the PATH, in turn, for a so-named executable / script, and execute the first one it finds (which might or might not be the MyScript you are intending to run). That's why specifying that you mean the very MyScript in this directory (./) is the better choice.
(*): Unless, of course, there is a function of that name defined.
#!/bin/bash
mydir=My/Folder/
cd $mydir
echo $(pwd)
MyScript
I would rather put the name in quotes. This makes it easier to read and save against mistakes.
#!/bin/bash
mydir="My Folder"
cd "$mydir"
echo $(pwd)
./MyScript
Your nickname says it all ;-)
When a command is entered at the prompt that doesn't contain a /, Bash first checks whether it is a alias or a function. Then it checks whether it is a built-in command, and only then it starts searching on the PATH. This is a shell variable that contains a list of directories to search for commands. It appears that in your case . (i.e. the current directory) is in the PATH, which is generally considered to be a pretty bad idea.
If the command contains a /, no look-up in the PATH is performed. Instead an exact match is required. If starting with a / it is an absolute path, and the file must exist. Otherwise it is a relative path, and the file must exist relative to the current working directory.
So, you have two acceptable options:
Put your script in some directory that is on your PATH. Alternatively, add the directory containing the script to the PATH variable.
Use an absolute or relative path to invoke your script.

diffstrings.py : how do you specify path arguments?

I am trying to use diffstrings.py from Three20 on my iPhone project, and I can't find the proper format for the path arguments (as in "Usage: diffstrings.py [options] path1 path2 ...").
For example, when I run the script in my Xcode project directory like this
~/py/diffstrings.py -b
it analyzes just the main.m and finds 0 strings to localize,
then it diffs against existing fr.lproj and others, and finds that thes contain "obsolete strings".
Can anyone post examples of successful comand line invocations of diffstrings.py, for options -b, -d and -m?
Taking a quick look at the code here http://github.com/facebook/three20/blob/master/diffstrings.py I see that if you don't specify any command line options, it assumes you mean the directory wherever the script lives in. So the option is to either copy .py file to where your .m files are, or simple use the command
~py/diffstrings.py -b .
That is, give the current directory (.) as the path argument.