Thread Subject:

LD_LIBRARY_PATH under linux

Hi,
I'm trying to set my LD_LIBRARY_PATH from within matlab under linux so it can find my .so that one of my .mexa64 requires...

If I try this:
p = getenv('LD_LIBRARY_PATH');
p = [p ':' pwd]
setenv('LD_LIBARARY_PATH', p);

I get the same OLD, unchanged LD_LIBRARY_PATH if I do another:
getenv('LD_LIBRARY_PATH')

I assume that matlab somehow detects me trying to change that and does not like that..

I there a normal way of achieving this from within matlab or do I have to do it externally from matlab.

Also, while on the subject...
How can I get this done in a matlab application?
I.e. if I pack the .so file inside the matlab app.. I probably need to somehow get the LD_LIBRARY_PATH or something else done to get it to work...

Any ideas?

"Dan Shecjter" <dans+matlab@houmus.org> wrote in message <h0qhdp$5o3$1@fred.mathworks.com>...
> Hi,
> I'm trying to set my LD_LIBRARY_PATH from within matlab under linux so it can find my .so that one of my .mexa64 requires...
>
> If I try this:
> p = getenv('LD_LIBRARY_PATH');
> p = [p ':' pwd]
> setenv('LD_LIBARARY_PATH', p);
>
> I get the same OLD, unchanged LD_LIBRARY_PATH if I do another:
> getenv('LD_LIBRARY_PATH')
>
> I assume that matlab somehow detects me trying to change that and does not like that..
>
> I there a normal way of achieving this from within matlab or do I have to do it externally from matlab.
>
> Also, while on the subject...
> How can I get this done in a matlab application?
> I.e. if I pack the .so file inside the matlab app.. I probably need to somehow get the LD_LIBRARY_PATH or something else done to get it to work...
>
> Any ideas?


TYou must set the variable LD_LIBRARY_PATH o in the .cshrc (or .bashrc, .tcshrc) file.

"Aurelien Queffurust" <tug83@yahoo.fr> wrote in message <h0qkbh$9rl$1@fred.mathworks.com>...
> "Dan Shecjter" <dans+matlab@houmus.org> wrote in message <h0qhdp$5o3$1@fred.mathworks.com>...
> > Hi,
> > I'm trying to set my LD_LIBRARY_PATH from within matlab under linux so it can find my .so that one of my .mexa64 requires...
> >
> > If I try this:
> > p = getenv('LD_LIBRARY_PATH');
> > p = [p ':' pwd]
> > setenv('LD_LIBARARY_PATH', p);
> >
> > I get the same OLD, unchanged LD_LIBRARY_PATH if I do another:
> > getenv('LD_LIBRARY_PATH')
> >
> > I assume that matlab somehow detects me trying to change that and does not like that..
> >
> > I there a normal way of achieving this from within matlab or do I have to do it externally from matlab.
> >
> > Also, while on the subject...
> > How can I get this done in a matlab application?
> > I.e. if I pack the .so file inside the matlab app.. I probably need to somehow get the LD_LIBRARY_PATH or something else done to get it to work...
> >
> > Any ideas?
>
>
> TYou must set the variable LD_LIBRARY_PATH o in the .cshrc (or .bashrc, .tcshrc) file.

Thank you for the answer. This obviously works.
But the real question for me is how do I get it to work with a matlab compiled app?
The files are embedded in the CTF...
I assume they get extracted somehwere on the file-system..
but how can I set the LD_LIBRARY_PATH externally when I don't know where to?

On Thu, 11 Jun 2009 05:06:01 -0400, Dan Shecjter <dans+matlab@houmus.org>
wrote:

> If I try this:
> p = getenv('LD_LIBRARY_PATH');
> p = [p ':' pwd]
> setenv('LD_LIBARARY_PATH', p);
> I get the same OLD, unchanged LD_LIBRARY_PATH if I do another:
> getenv('LD_LIBRARY_PATH')


This works for me with R2008b on Debian 4.0.

On Thu, 11 Jun 2009 06:59:03 -0400, Dan Shechter <dans+matlab@houmus.org>
wrote:

> But the real question for me is how do I get it to work with a matlab
> compiled app?
> The files are embedded in the CTF...


  CTFROOT Returns the root of the application in deployed mode.
      ROOT = CTFROOT returns the string that is the name of the directory
      where the CTF file for the deployed application is exploded.

Dan Shechter <dans+matlab@houmus.org> wrote:
> "Aurelien Queffurust" <tug83@yahoo.fr> wrote in message <h0qkbh$9rl$1@fred.mathworks.com>...
>> "Dan Shecjter" <dans+matlab@houmus.org> wrote in message <h0qhdp$5o3$1@fred.mathworks.com>...
>> > Hi,
>> > I'm trying to set my LD_LIBRARY_PATH from within matlab under linux so it can find my .so that one of my .mexa64 requires...
>> >
[snip]

>>
>> TYou must set the variable LD_LIBRARY_PATH o in the .cshrc (or .bashrc,
.tcshrc) file.
>
> Thank you for the answer. This obviously works.
> But the real question for me is how do I get it to work with a matlab
compiled app?
> The files are embedded in the CTF...
> I assume they get extracted somehwere on the file-system..
> but how can I set the LD_LIBRARY_PATH externally when I don't know where
to?

The usual thing to do is to specify the expected location of your libraries
on the link line when building the application. Tell your end users that
you expect to either have the libraries in the specified location (e.g.
/usr/local/lib or /opt/mystuff/lib or whatever), or in the system expected
location (/usr/lib or whatever). Otherwise, have them set the
LD_LIBRARY_PATH.

I believe MATLAB handles this by having a wrapper script around the actual
executable. The script takes care of paths etc, then calls the executable.
This is kind of why your attempt to set the variable from within MATLAB
fails. You can set the environment variable using the unix command or the
!, but that is only valid for within the shell for that command.

You might do this:

>> unix('setenv MYTHING fish;echo $MYTHING');
fish
>> unix('echo $MYTHING');
MYTHING: Undefined variable.
>>

So the subsequent call knows nothing of what you did before, because it is
in a separate shell.

--
Dr Tristram J. Scott
Energy Consultant

<rant>
Original poster's problem drives me crazy. Ridiculous matlab behavior (I'm on 2009a). By modifying LD_LIBRARY_PATH, you can only add stuff to the end of the ld library path. But Matlab will not allow you to have, say, /the/path/i/need prior to matlabroot/sys/os/glnxa64.

so I need to link my stuff statically? don't like it at all!
</rant>

Hi, can anyone let me know if there has been progress on this issue / if there is any solution? I've been trying to do the same thing (change LD_LIBRARY_PATH from a mex file while MATLAB is running), but the change is not recognized.

"James " <a@b.com> wrote in message <h2ja2p$sst$1@fred.mathworks.com>...
> <rant>
> Original poster's problem drives me crazy. Ridiculous matlab behavior (I'm on 2009a). By modifying LD_LIBRARY_PATH, you can only add stuff to the end of the ld library path. But Matlab will not allow you to have, say, /the/path/i/need prior to matlabroot/sys/os/glnxa64.
>
> so I need to link my stuff statically? don't like it at all!
> </rant>

"Aurelien Queffurust" <tug83@yahoo.fr> wrote in message <h0qkbh$9rl$1@fred.mathworks.com>...
> "Dan Shecjter" <dans+matlab@houmus.org> wrote in message <h0qhdp$5o3$1@fred.mathworks.com>...
> > Hi,
> > I'm trying to set my LD_LIBRARY_PATH from within matlab under linux so it can find my .so that one of my .mexa64 requires...
> >
> > If I try this:
> > p = getenv('LD_LIBRARY_PATH');
> > p = [p ':' pwd]
> > setenv('LD_LIBARARY_PATH', p);
> >
> > I get the same OLD, unchanged LD_LIBRARY_PATH if I do another:
> > getenv('LD_LIBRARY_PATH')
> >
> > I assume that matlab somehow detects me trying to change that and does not like that..
> >
> > I there a normal way of achieving this from within matlab or do I have to do it externally from matlab.
> >
> > Also, while on the subject...
> > How can I get this done in a matlab application?
> > I.e. if I pack the .so file inside the matlab app.. I probably need to somehow get the LD_LIBRARY_PATH or something else done to get it to work...
> >
> > Any ideas?
>

 
> TYou must set the variable LD_LIBRARY_PATH o in the .cshrc (or .bashrc, .tcshrc) file.

That is not true on Macs. For those I had to use the same method as OPs original solution.
Why Mac and Linux behave differently? That's crazy.

Sorry, don't have much constructive to add, but to save other people the time trying, I thought I'd note that even linking the paths into a mex file using -rpath doesn't help. MATLAB STILL overrides the library paths. I don't even know how it does that...!

<rant>

TMW PLEASE NOTE: This is unacceptable!

At the very least, if you're forcing us to link to your libraries, make them thread-safe. It's not 1980 any more... People like to use all the cores on their processors. I've got memory leaks galore which I can't fix because you won't let me link against a library that works!

So I have three alternatives at the moment:
1. Not complete my PhD (Using sequential code will be so slow it'll take me past the deadline by a few months)
2. Use OCTAVE.
3. Carry on wasting days (weeks, really) deleting MATLAB library files and replacing them with symlinks to Intel/gnu ones then re-running VALGRIND to see whether the problem is fixed or not.

<end rant. sorry>

"Thomas Clark" wrote in message <j3d720$ro2$1@newscl01ah.mathworks.com>...
> Sorry, don't have much constructive to add, but to save other people the time trying, I thought I'd note that even linking the paths into a mex file using -rpath doesn't help. MATLAB STILL overrides the library paths. I don't even know how it does that...!
>
> <rant>
>
> TMW PLEASE NOTE: This is unacceptable!
>
> At the very least, if you're forcing us to link to your libraries, make them thread-safe. It's not 1980 any more... People like to use all the cores on their processors. I've got memory leaks galore which I can't fix because you won't let me link against a library that works!
>
> So I have three alternatives at the moment:
> 1. Not complete my PhD (Using sequential code will be so slow it'll take me past the deadline by a few months)
> 2. Use OCTAVE.
> 3. Carry on wasting days (weeks, really) deleting MATLAB library files and replacing them with symlinks to Intel/gnu ones then re-running VALGRIND to see whether the problem is fixed or not.
>
> <end rant. sorry>

One kind of dirty solution that seems to work for me is the following:
make it a standalone application using mcc
add the library path to the run_myfunc.sh script MANUALLY.
run it
Probably you will have to deal with some additional problems such as dependencies to 3rd software etc