MATLAB Answers

couldn't run codegen under matlab

22 views (last 30 days)
Qingyan
Qingyan on 25 May 2011
I have trial version of matlab coder,and download a sample coder from mathwork: hello_world. and followed the instruction of how to setup and run the sample.
when I tried to run codegen to generate mex function within matlab, I get a error message like: >> codegen hello_world ??? cp: preserving permissions for `/var/local/scratch/qguan/coder2/coderdemo_hello_world/codegen/mex/hello_world/mexopts.sh': Operation not supported
I checked uid and gid for the current workfolder, it is set all fine and rw enabled.
what else I should be looking into? or is it known issue?
Thanks so much for your help! Qingyan

  0 Comments

Sign in to comment.

Accepted Answer

John Elliott
John Elliott on 26 May 2011
The codegen command uses
>> copyfile(<source_file>,<dest_dir>,'f')
to copy mexopts.sh, which is typically found in [matlabroot '/bin']. You could try executing this command to see if it fails.
If the issue is related to permissions, you might try running mex -setup. This can be used to copy mexopts.sh to your prefdir (to which I presume you have write permission) and you could then modify the permissions on the file in your prefdir. The codegen command will give preference to the mexopts.sh file in the prefdir over the one in the bin directory.
-John

  6 Comments

Show 3 older comments
Walter Roberson
Walter Roberson on 26 May 2011
Insert a new "cp" earlier on your PATH that strips out the -p and passes the rest to the real cp ;-)
Qingyan
Qingyan on 31 May 2011
as this is a matlab code, it only uses copyfile(), which actually run cp -p in OS system. doesn't that mean that I have modify matlab function copyfile()? otherwise, I don't know how to strip out the -p.
I think what I will do is to modify matlab startup folder, so it can land to local directory, to avoid involving NFS files.
Thanks everyone for help!
Walter Roberson
Walter Roberson on 31 May 2011
If it actually invokes "cp" then the operating system is going to use the PATH environment variable to search for "cp". If you have provided a PATH environment variable that first lists a different directory that has your own version of "cp" in it, the operating system would look there first. The program you have in that location could process the arguments, remove the "-p" and start the _real_ "cp" program with those arguments.
But changing your start-up directory is probably easier ;-)

Sign in to comment.

More Answers (1)

Walter Roberson
Walter Roberson on 25 May 2011
It sounds as if at some point the script is executing the Linux command
cp -p SomeFile /var/local/scratch/qguan/coder2/coderdemo_hello_world/codegen/mex/hello_world/mexopts.sh
(Or --preserve instead of -p)
and that for some reason keeping the permissions is not possible.
Sometimes preserving permissions is not possible with networked file systems.
What I would probably do is fine the "cp" line and remove the "-p" or "--preserve" option.

  6 Comments

Show 3 older comments
Qingyan
Qingyan on 25 May 2011
I removed sgid from the working folder,it still does not work.
Under matlab the command copyfile is equivalent to unix command cp -p, so I run copyfile function under matlab console, it seems working fine.
Walter, could you show me how to do the strace to get idea which script it is running.
Walter Roberson
Walter Roberson on 25 May 2011
The documentation for copyfile is inconsistent with copyfile being equivalent to cp -p . The copyfile documentation indicates, "The read-only and archive attributes of source are not preserved in destination." but the point of cp -p is to preserve at least the read-only attribute.
Kaustubha Govind
Kaustubha Govind on 26 May 2011
@Qingyan: Have you tried running either:
!cp -p /some/source /some/destination
or
system('cp -p /some/source /some/destination')
Do they work okay?

Sign in to comment.