System command 'cd' not working

I am experiencing a problem when trying to use the Matlab system command 'cd' to change the current system directory. On my laptop, it works fine. However, on my university desktop machine (networked mac pro), it doesn't seem to want to work no matter what I do.

For example, say I start in the directory /test. I verify this by typing > !pwd , which tells the system to print the current directory.

If I then assign a matlab variable a path string e.g.

> datapath = '/anotherdirectory/test2'

and then try to change into it by typing

> cd(datapath)

When I do this on my laptop, !pwd returns /anotherdirectory/test2. However, on my desktop, !pwd returns /test. No matter what I do, cd will not change the system directory outside the Matlab environment on my work machine. I've tried all sorts of variants to get the cd command to work such as

> system(horzcat('cd ',datapath))

as well, but without success. This is becoming a major pain for me, because none of my data reduction scripts are going to function if I cannot get this functionality to work without MAJOR overhauls. Anyone got any ideas? Perhaps it is some sort of permissions issue with my work machine, where it won't allow another program to perform system commands or something?

Answer 1

[Daniel Shub]

From your comment to Walter, it seems you are trying to change the directory of the "shell" from within MATLAB. It is not really clear what this means. What do you get if you do something like:

[a,b] = system('pwd; cd .. ; pwd')

This will be different then

!pwd
!cd ..
!pwd

The second case starts a new shell before and exits the shell after every command. The first case only create a single shell. How are you making your system calls?

[Craig Anderson]

Thanks a heap Daniel - you've saved my world from imploding in on itself. Your first command does the trick nicely. Funny though that either set of commands works on my laptop though. I suspect that this is possibly due to the issue that Mr. Govind mentioned below...

[Marco A. Acevedo Z.]

Note that the system() function do not allow changing directory between different disks in the PC. You are trapped in either C: or D: and will need to do cd() function before and after the call to produce the desired effect. This is important because you wont be able to call external functions between paths (if in different disks) added to the same script.

[Walter Roberson]

@Marco A. Acevedo Z.

https://www.geeksforgeeks.org/cd-cmd-command/

system('cd /D D:\New\Path\Goes\Here; appropriate command goes here')

[Marco A. Acevedo Z.]

Thanks for the tip. My previous comment is not longer valid. Note that the ' /D ' represents the word 'another drive', not the letter of a different disk that follows up. :)

Cheers,

Answer 2

[Walter Roberson]

The first thing I would suggest trying is

which -all cd

just in case you somehow have introduced your own cd.m file .

Also, what does pwd (without the '!') return in each case?

[Walter Roberson]

And of course on the desktop I would check that /anotherdirectory/test2 exists on the machine, and doesn't happen to be a symbolic link to /test

[Craig Anderson]

Hi Walter,

Thanks for the reply.

- The directory exists and is not a symbolic link.

- which -all cd returns:

which -all cd

built-in (/Applications/MATLAB_R2010b.app/toolbox/matlab/general/cd)

/Applications/MATLAB_R2010b.app/toolbox/matlab/iofun/@ftp/cd.m % ftp method

-pwd without the bang shows that the command is at least changing the directory within Matlab. That is, using >cd(datapath) as per my original question and then typing >pwd returns '/anotherdirectory/test2'. cd('/') and then pwd again returns '/'. It seems to be changing the current directory in matlab without a problem, but not as far as the system itself goes.

The problem is that my data reduction script largely consists of a bunch of file handling routines, and wrapper function calls to miriad - a radio astronomy data reduction program. For miriad to put files in the correct place during the reduction, the system directory needs to be set to where I want the files to end up. Not being able to use cd means that this is a big problem considering the amount of data that I have to run through it!

[Kaustubha Govind]

Does your shell startup script always force the shell to start in a certain directory? I've seen that this has been the most likely cause for these issues in the past. One good way of testing this is to start a new shell window from within MATLAB and check if it always opens in a certain directory. I'm not familiar with Mac, but on Windows, you would use something like "!start &" to start a new system command window.

[Craig Anderson]

Thanks for that! I'll go and check this out too. Much appreciated!

Answer 3

[Konrad Gromaszek]

Hello,

On my Mac code I've used

path_str = './MLP';
cd(path_str);

instead of

cd('./MLP');

... and it works!